What best describes the hind leg bones seen in the baleen whale?

Explanation

In baleen whales, vestigial pelvic bones are examples of structures that had a function in their ancestors. These bones are remnants of hind limbs, which would have been functional in the land-dwelling ancestors of whales. Although these pelvic bones no longer serve their original purpose of supporting hind limbs, they have not entirely disappeared. Instead, they persist as small, internal bones near the tail and are thought to play a minimal role in reproductive organ support rather than locomotion. This vestigial structure provides insight into the evolutionary transition of whales from land-dwelling mammals to fully aquatic animals.