Smooth muscles are spindle shaped. They have a single nucleus and are involuntary muscles.

Communication junctions or intercalated discs at some fusion points allow the cardiac muscle fibres to contract as a single unit.

Diagram ‘a’ shows cardiac muscles. It has striations and intercalated discs and is exclusively present in heart, hence present in the nodal tissues.). Diagram ‘b’ depicts skeletal or voluntary muscle. They have stripes or striations on them. Such muscles are found in the biceps, pectoral region. Diagram ‘c’ shows smooth muscles which are involuntary and do not have any striations on them. They are found in internal organs like walls of blood vessels, stomach.

Involuntary smooth muscles are those muscles that are not under the control of our will and are without any striations. Iris has involuntary smooth muscle. Biceps of the upper arm have striated muscle fibers and the abdominal wall has involuntary smooth muscles. Heart wall has cardiac muscles which have striated appearance, and they are involuntary.

Cardiac muscle tissue is a contractile tissue present only in the heart. Cell junctions fuse the plasma membranes of cardiac muscle cells and make them stick together. Communication junctions (intercalated discs) at some fusion points allow the cells to contract as a unit, i.e., when one cell receives a signal to contract, its neighbours are also stimulated to contract.

 - Skeletal muscles are attached to our skeletal bones and perform voluntary functions.
- Smooth muscles are spindle shaped (tapering at both ends) and are found in internal organs.
- Intercalated discs are a characteristic feature of cardiac muscle.
Therefore, option (c) is correct

cardiac muscles are present in the heart. These are striated, involuntary and have intercalated discs which differentiate them from skeletal muscles which are striated, voluntary and lack intercalated discs.

Smooth muscles are spindle- shaped in outline with broad middle part and tapering ends, are unbranched, unstriated, uninucleate and are involuntary.

Involuntary smooth muscles are those muscles that are not under the control of our will and are without any striations. Iris has involuntary smooth muscle. Biceps of the upper arm have striated muscle fibres and abdominal wall has involuntary smooth muscles. Heart wall has involuntary striated muscle. Heart walls are cardiac muscles.
Hence, the correct option is (d).

- A muscle is composed of bundles of muscle fibres. 
 - Each bundle is composed of numerous muscle fibres or muscle cells.
 - These muscle fibres are composed of myofibril or myofilaments having actin and myosin bands.

Diagram ‘a’ shows cardiac muscles. It has striations and intercalated discs and is exclusively present in heart and hence, present in the nodal tissues (nodes of heart). Diagram ‘b’ depicts skeletal or voluntary muscles i.e., they are under conscious control. They have stripes or striations on them. Such muscles are found in the biceps, pectoral region, etc. Diagram ‘c’ shows smooth muscles which are involuntary and do of have any striations on them. They are found in internal organs like walls of blood vessels, stomach, etc. Thus, option (c) is correct.

The muscles are of three types- Skeletal, smooth and cardiac muscles. Skeletal muscles are also called voluntary muscles as they are voluntary in function. Smooth muscles are present in internal organs and can be termed as visceral muscles. They are involuntary in function i.e., not under our conscious control and hence can also be called as involuntary muscle. Cardiac muscles are present exclusively in the heart.

- Skeletal muscles are attached to our skeletal bones and perform voluntary functions.
 - Smooth muscles are spindle shaped (tapering at both ends) and are found in internal organs.
 - Intercalated discs are a characteristic feature of cardiac muscle.
 Therefore, option (c) is correct.

- All muscles are mesodermal in origin. 
 -During embryonic stages the three germ layers ectoderm, mesoderm and endoderm form the tissues and organs of the body. Mesoderm forms connective tissues, muscles, heart, etc.

The cytoplasm of a myocyte or muscle fibre is called sarcoplasm. Sarcolemma is the membranous sheath covering each muscle fibre. The cytoplasm of neurons or nerve cells is called neuroplasm. Nucleoplasm refers to the cytoplasm-like content inside the nucleus of the cell.

-Striations present in the striated muscles are due to the specialized arrangement of myofilaments (actin and myosin).
 -Actin filaments make lighter bands and myosin filaments make darker bands. They are arranged in a specific pattern which gives the appearance of striations on the muscle fibre.

When a number of cells fuse together, their nuclei are present in the same region, this multinucleate cytoplasm is called a syncytial cytoplasm/cell. This condition is observed in skeletal muscles. Polyploidy is a condition where the cells contain more than two sets of chromosomes like tetraploid, hexaploidy, etc. 

- Striated/ Skeletal muscles have multinucleated or syncytial in nature. 
 - Non-striated or smooth muscles are uninucleate. Other options are also among uninucleate cells.

Skeletal/striated muscles are cylindrical in shape and run parallel to each other. It shows multinucleate condition (syncytial). It is unbranched and voluntary in function. Hence, option (c) correctly identifies striated muscles.

Sarcomere is the fundamental repeating unit of a skeletal muscle fibre. Each sarcomere has actin and myosin filaments arranged in such a way that facilitates the contraction and relaxation of the muscle. The part of myofibril between two Z-lines is termed as sarcomere.

Cardiac muscles are present only in the heart. They are striated and involuntary in function i.e., they are not under our conscious control. They are branched and have intercalated discs for rhythmic contraction and relaxation of heart muscles.

Intercalated discs are a characteristic feature of cardiac muscles (heart muscles). These are not found in any other type of cell. These intercalated discs help in cell-to-cell communication and thus make the muscles of the heart contract and relax rhythmically.

Simple columnar epithelium is found in the inner lining of the stomach and intestine. These cells help in secretion and absorption of nutrients. Cardiac muscles are found in the heart. Adipose tissues are fat storing tissues and found below the skin, thighs, breasts, etc. Hyaline cartilage is a cartilage which is almost transparent in appearance and found in ribs and sternum to protect the bones from friction while movement.

Smooth muscles are found in the posterior part of oesophagus, stomach, intestine, blood vessels, iris of eye and dermis of skin. They are involuntary as their functioning cannot be directly controlled. Action of these muscles is controlled by autonomic nervous system.

The wall of internal organs such as the blood vessels, stomach and intestine contains smooth muscles. The type of muscles that are closely associated with bones are skeletal muscles.

-Unicellular glandular cells are present in goblet cells.
 -Exocrine gland secrete saliva.
 -Smooth muscles taper at both ends, hence, fusiform.
 -Cartilage is a type of specialized connective tissue.