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:

1. Both A and R are true, and R is correct explanation of the assertion.
2. Both A and R are true, but R is not the correct explanation of the assertion.
3. A is true but R is false.
4. A is false but R is true.

Assertion: Internal fertilisation occurs in mammals and birds.

Reason: External fertilisation occurs in reptiles, amphibians, and fishes.