53. Which of the followings would a paleontologist be most likely to do in order to determine whether a fossil represents areptile or a mammal?
(A) Look for the mammalian characteristics of a four-chambered heart and a diaphragm.
(B) Because mammals are eutherians, look for evidence of a placenta.
(C) Use molecular analysis to look for the protein keratin.
(D) Examine the teeth.
(E) Look for the presence of milk-producing glands.