The question is incomplete. The complete question is as following:
In humans, the pelvis and the femur, or thighbone, are involved in walking. In whales, the pelvis and femur shown in this figure represent...
Answer:
vestigial structures
Step-by-step explanation:
A "vestigial structure" or "vestigial organ" are defined as the organs that no longer have any function in the organisms' body but had an important role in past.
Pelvis and femur are thigh bones in humans which helps them in walking but in whale's pelvis and femur are considered as vestigial structures.
The pelvis and femur in whales, are the inherited structure from ancestors and shows evidence for evolution on the basis of natural selection.
Hence, the correct answer is vestigial structures.