$\text{Directions:}$ Choose the correct option:

Assertion $\left(A\right):$ Crocodile has a four-chambered heart.

Reason $\left(R\right):$ Crocodile is a reptile.

1. Both assertion$\left(A\right)$ and reason$\left(R\right)$ are true, but reason$\left(R\right)$ is not the correct explanation for assertion.

2. Both assertion$\left(A\right)$ and reason$\left(R\right)$ are true and reason(R) is the correct explanation for assertion$\left(A\right).$

3. Assertion$\left(A\right)$ is true and reason$\left(R\right)$ is false.

4. Assertion$\left(A\right)$ is false and reason$\left(R\right)$ is true.

The correct option is A

Both assertion$\left(A\right)$ and reason$\left(R\right)$ are true, but reason$\left(R\right)$ is not the correct explanation for assertion.

Correct option: $\left(b\right)$Both assertion$\left(A\right)$ and reason$\left(R\right)$ are true, but reason$\left(R\right)$ is not the correct explanation for assertion.

$\bullet$ Reptiles are characterised by the presence of a three-chambered heart.

$\bullet$ Crocodiles belong to the class Reptilia but have a four-chambered heart.

$\bullet$ Their heart consists of two atria and two ventricles.

$\bullet$ So the correct option is $\left(b\right).$