Assertion: Diversity observed in the entire geographical area is called gamma diversity.

Reason: Biodiversity decreases from high altitude to low altitude.

(a) If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.

(b) If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.

(c) If Assertion is correct but Reason is incorrect.

(d) If both the Assertion and Reason are incorrect.