The class mammalia contains the only animals that

Have mammary glands - GradPoint answer (you can do this)

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.

i really wish i could answer this question for you

nucleic acid molecules are incredibly complex, containing the code that guarantees the four different nucleotide units comprise dna, the nucleic acid of interest to the genealogist. and one of four nitrogen-containing molecules called nucleotides