Which of the following refers to the diversity of available genes within a population? A) demographics
B) genetic variety
C) gene pool
D) population distribution
E) tolerance range

gene pool

Explanation:

"A gene pool is the total genetic diversity found within a population or a species. A large gene pool has extensive genetic diversity and is better able to withstand the challenges posed by environmental stresses."

source: https://www.genome.gov/genetics-glossary/Gene-Pool#:~:text=A%20gene%20pool%20is%20the,challenges%20posed%20by%20environmental%20stresses.

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