Which of the following is a vestigial structure in the human body?

Explanation

The appendix is the reduced remains of a large caecum that digests cellulose in herbivorous ancestors, and it can be removed with no loss of digestive function. Vestigial organs are evidence of evolution precisely because a designed structure would not carry a useless remnant. The pancreas and diaphragm are fully functional, and the thymus, though it shrinks after puberty, is essential for training T lymphocytes.