Among the following sets of salient features, which set

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

1. Presence of sweat glands, hairs on skin and diphyodonts
2. Presence of mammary glands, sweat glands and diaphragm
3. Presence of mammary glands, sweat glands and diaphragm
4. Presence of mammary glands, hairs on skin and diaphragm.

Aves are also worm blooded and their heart is four-chambered. Crocodiles (Reptilia) also have fourchambered heart.