Given below are two statements. One is labelled Assertion (A) and the other is labelled Reason (R).

Assertion (A) : Darwin's finches exhibit adaptive radiation.

Reason    (R)  : Different varieties of finches with different food habits evolved from original seed-eating ancestor.

In light of the above statements, choose the correct answer from the options given below.

Both (A) and (R) are true and (R) is the correct explanation of (A).  

• Assertion (A) is true. Darwin's finches, a group of birds native to the Galápagos Islands, are a classic example of adaptive radiation. Adaptive radiation refers to the diversification of a single ancestral species into multiple species, each adapted to exploit different ecological niches or environments.
• Reason (R) is also true, and it provides the correct explanation for Assertion (A). Darwin's finches evolved from a common ancestor, likely a seed-eating bird that arrived on the Galápagos Islands from the mainland. Over time, as these birds adapted to the diverse environmental conditions and food sources available on different islands of the archipelago, they diversified into different species with specialized beak shapes and feeding habits. This diversification enabled them to exploit various food resources, such as seeds, insects, fruits, and nectar, leading to the evolution of different varieties of finches with distinct ecological roles. Therefore, Reason (R) accurately describes how different varieties of finches with different food habits evolved from a common ancestor, supporting the concept of adaptive radiation in Darwin's finches.