Which structure evolved in finches, allowing them to become insectivorous and vegetarian?

What is the most important pre-condition for adaptive radiation?

On which island did Darwin observe many varieties of finches?

The finches of Galapagos islands provide evidence in favor of:

Given below are two statements with respect to homologous organs.
Statement $I$: These organs are structurally similar but perform different functions.
Statement $II$: Differences in homologous organs are examples of adaptive radiation.
In the light of the above statements,choose the correct option from the list given below.

Adaptation is a type of ......