Glands are secretory structures that produce various important biological secretions. The coiled tubular glands are made of a very long and unbranched duct. This duct continues with the coiled portion which is the secretory portion. An example of this is the eccrine sweat gland. Complete answer:
Glands are structures of cells that synthesize and secrete substances such as hormones, oils, sweat, etc. either inside the body or on its outer surface. There are two major types of glands. These are called exocrine glands and endocrine glands. The endocrine gland products circulate along with the bloodstream whereas exocrine gland products are secreted through a duct. The secretion of exocrine glands passes through ducts that terminate either externally to the skin or internally to organs.
Simple coiled tubular glands have a very long duct which is a cylindrical structure. The duct terminates outside the skin surface and thus it is an exocrine gland. The base of the coiled tubular gland is coiled and it is the main secretory region. These glands are usually unbranched. An example of these glands is the eccrine gland. It is the major sweat gland that lies in the dermis layer of the skin. All of the skin consists of these glands. Palm, head, and sole regions contain these glands in high density. Their secretion is a clear odorless substance called sweat. It primarily consists of water. The secretions are excreted through sweat pores on the skin. Therefore, from the above discussion, we can conclude that the right answer is option A. Note:
The coiled portion of the simple coiled tubular glands is made of two concentric layers of columnar or cuboidal epithelial cells. Myoepithelial cells interpose the underlying epithelial cells. Above the myoepithelial cells lie the secretory epithelial cells.