Question

which of the following is an example of darwins theory of evolution?
giraffes stretch their necks during their lifetime, so their offspring inherit longer necks.
finches on separate islands have different beak shapes depending on the food sources available.
a person lifts weights and becomes strong, and their children are born with more muscles.

Explanation:

Darwin's theory of evolution emphasizes natural selection. In the case of finches on separate islands, different food sources lead to natural selection of beak shapes that are advantageous for obtaining that food. This is in line with Darwin's theory. The giraffe example is more related to Lamarckian inheritance (acquired traits being passed on, which is not Darwin's main idea). The person lifting weights example also involves acquired traits (muscle development) being passed on, which is not in line with Darwin's theory.

Answer:

Finches on separate islands have different beak shapes depending on the food sources available.