Hint: Inside the ovum yolk, ribosomes, mitochondria, endoplasmic reticulum are present. The ribosomes are required for the synthesis of proteins and mitochondria provides energy to the ovum. The Golgi apparatus helps in the packaging of proteins into small vesicles.
Complete answer: • Ovum is produced from the oogonia through the process of oogenesis. After the maturation and the first meiotic division, a tiny polar body is also formed. • The yolk of the ovum consists of the cytoplasm, which is very similar to that of the animal cell, and the nutritive yolk which consists of fat granules and albuminoidal substances. The main function of the nutritive yolk is to provide nourishment to the growing embryo. • The zona pellucida and the corona radiata are the layers which surround the ovum. • The Ovum is the female gamete. It consists of all the required cell organelles. But the ovum lacks in centrosomes. This is so because after the second maturation, polar bodies are formed. These polar bodies take away the centrosomes. • External yolk sacs do not show any clinical significance and the yolk sac is visible from 5 week of gestation period.
Hence, the correct answer is option (C).
Note: We know that the sperm fertilizes the ovum to form the zygote. Here it must be noted that since the ovum lacks the centrosomes, therefore it is the sperm which gives its proximal centriole so that the spindle apparatus is formed after the first cleavage of the zygote.