Researchers have historically considered the human appendix to be a vestigial structure. what evidence, if true, would best disprove this claim? a. the appendix was used to digest leaves in the ancestors of humans, but it appears to serve no function in modern humans. b. cows have an appendix to them digest grass, but it evolved independently from the appendix found in humans. c. the human appendix to maintain the health of the gut, and arose fairly late in the evolutionary history of mammals. d. chimpanzees also have an appendix, and humans and chimpanzees inherited the appendix from the same ancestor.