Answer:
Sperm whales evolved from ancestors that walked on land.
Step-by-step explanation:
A vestigial structure is a body part that is present in an organism, but serves no function due to evolution over time. An example of a vestigial structure would be a human's tail bone.
Sperm whales contain vestigial hip bones, meaning that the organisms once had legs. Therefore, the answer that is the most accurate is that sperm whales evolved from ancestors that walked on land.