Question

Which characteristics are found only in mammals?

• A. Pinna, teeth
• B. Hair, oviparity
• C. Mammary gland, teeth
• D. Hair, mammary gland

Answer 1

The correct option is D Hair, mammary gland

The key characteristic of mammals is the adaptation of skin glands, such as hair follicles and mammary glands. Bodies of mammals are typically covered with hair which has no structural homology in other vertebrates. Mammary glands secrete milk that are used for the nourishment of the young one during their postnatal period of rapid growth.

Hence, option D is correct.