What most likely caused the finches on the Galapagos Islands to have beaks that were different from the finches living on the South American mainland?

Question

What most likely caused the finches on the Galapagos Islands to have beaks that were different from the finches living on the South American mainland?

Responses

The finches on the islands had to drink salt water.

There were different types of predators living on the island.

The finches on the mainland built different types of nests.

There were different types of food available on the island.

Answer 1

There were different types of food available on the island.

Answer 2

The most likely cause for the finches on the Galapagos Islands to have beaks that were different from the finches living on the South American mainland is that there were different types of food available on the island.