Q.

The unique mammalian characteristics are:                 [2023]

1 Hairs, pinna, and indirect development  
2 Pinna, monocondylic skull, and mammary glands  
3 Hairs, tympanic membrane, and mammary glands  
4 Hairs, pinna, and mammary glands  

Ans.

(4)

The unique mammalian characters are mammary glands (milk-producing glands), the presence of hair, and external ears or pinnae.