There is some evidence that reptiles called cynodonts may have had whisker-like hairs around their mouths. If true, then hair is a shared: a. ancestral character of the reptiles and mamma
b. derived character of mammals, but only if cynodonts are reclassitied as mammals
c. derived character of mammals, even if cynodonts continue to be classified as reptiles
d. ancestral character of the mammal clade but not the reptiles clade.