Respuesta :
Answer: The correct answer for the blank is-
The class mammalia contains the only animals that have mammary glands.
Explanation:
Mammalia is considered as class of higher vertebrates (such as , marsupials, placentals, or monotremes) that provide nourishment to their offspring through mammary glands, which secrete milk.
They are warm blooded organisms and their skin is usually covered with more or less hairs.
Example- Human beings.
