Answer:
The correct option is A) if species living on different islands had once been members of the same species.
Explanation:
During his voyage on the H.M.S Beagle, Charles Darwin observed that different parts of the Galapagos island comprised of organisms of similar species carrying different traits. By observing these characteristics like the 13 different types of finches he thought that whether it would have been possible that all these organisms once had a common ancestor. His thinking led him to the formulation of theory of natural selection which is accepted by many scientists even today.
