Yes Darwin’s theory of natural selection
Answer: D. Keratin
Explanation: Keratinocytes (pronounced: ker-uh-TIH-no-sites) make keratin, a type of protein that's a basic component of hair, skin, and nails. Keratin in the skin's outer layer helps create a protective barrier.
They don't reproduce, as far as I know. They are produced in bone marrow.
Answer:
yes
Explanation:
creatine like horns of rhinos or finger nails