For two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below: a. Both A and R are true, and R is correct explanation of the assertion. b. Both A and R are true, but R is not the correct explanation of the assertion. c. A is true but R is false. d. A is false but R is true. Assertion: Internal fertilisation occurs in mammals and birds. Reason: External fertilisation occurs in reptiles, amphibians, and fishes.