[A] : Bats and whales are mammals
[R] : They have 4 chambered heart .

Options

A. If the both assertion and reason are true and the reason is the correct explanation of the assertion
B. If both assertion and reason are true and the reason is not the correct explanation of the assertion
C. If assertion is true but reason is false
D. If both assertion and reason are false statements.

Answer

B

Explanation

Bats and whales are classified as mammal because they posses the essential mammalian characteristics like presence of milk gland or mammae, presence of pinnae, vivparous nature , hairs on body, presence of diaphragm etc. Though bats and whales have four chambered heart, it cannot be considered as the main characteristic of being mammals because it is alse present in some reptiles ( e.g crocodile) and all birds.