A scientist is comparing the sequences of related genes among three species. Two of the species have very similar sequences, while the sequence of the third species differs greatly from the others. The scientist uses this comparison to propose an evolutionary history of the species. Which statement best explains the usefulness of the evidence that the scientist gathered?

A. Mutations can act as a molecular clock that show when species had a common ancestor.

B. Changes in gene sequences generally occur when two species interbreed.

C. Changes in gene sequences generally occur when one species evolves into another species.

D. Although some mutations have little effect, many mutations act to distinguish one species from another.