There is some evidence that reptiles called cynodonts may have had whisker-like hairs around their mouths. If true, then what can be properly said of hair?

A) It is a shared derived character of mammals, even if cynodonts continue to be classified as reptiles.
B) It is a shared derived character of the amniote clade, and not of the mammal clade.
C) It is a shared ancestral character of the amniote clade, but only if cynodonts are reclassified as mammals.
D) It is a shared derived character of the mammals, but only if cynodonts are reclassified as mammals.