Among the following sets of salient features, which set does not exclusively characterise mammals?

A. Presence of sweat glands, hairs on skin and diphyodonts

B. Presence of mammary glands, sweat glands and diaphragm

C. Absence of mammary glands, sweat glands and diaphragm

D. Presence of mammary glands, hairs on skin and diaphragm

Answer: Option C