Darwin realized that variation must be the starting point for change in nature. In any generation, the animals in a litter are never quite the same. And in the wild, such a tiny might make all the difference between life and death.

Darwin realized that existing heritable variation in a generation must be the starting point for a change in nature. In any generation, the animals in the litter are never quiet the same. And in the wild,such a tiny heritable variation might make all the difference between life and death.

Explanation:

Refer below.

Explanation:

Darwin realized that variation must be the starting point for change in nature. In any generation, the animals in a litter are never quite the same. And in the wild, such a tiny variation might make all the difference between life and death.

i think the answer is a.keratin is the pigment responsible for skin color.