The amino acid sequence of cytochrome c is exactly the same in humans and chimpanzees. There is a difference of 13 amino acids between the cytochrome c of humans and dogs, and a difference of 20 amino acids between the cytochrome c of humans and rattle snakes. Which of the following is best supported by these data?
a. Rattlesnakes apparently gave rise evolutionarily to the dog, chimpanzee, and human.
b. Cytochrome c apparently has an entirely different function in rattlesnakes than in mammals, which explains the difference in the number of amino acids.
c. Cytochrome c is not found universally in animals.
d. Cytochrome c from a rattlesnake could function in a dog, but not in a chimpanzee.
e. The human is apparently more closely related to the chimpanzee than to the dog or rattlesnake.