Environmental factors can influence natural selection because they can increase or decrease:

A. the number of chromosomes in an individual.

B. the number of chromosomes in a population.

C. the amount of genetic variation in an individual.

D. the amount of genetic variation in a population.

Answer

D. the amount of genetic variation in a population.

Explanation:

Environmental factors (such as climate, predators, food sources, and disease) play a major role in natural selection by influencing which traits are favorable for survival and reproduction. These pressures can increase or decrease genetic variation within a population, not within a single individual.

Greater variation allows a population to better adapt to changes in the environment. If variation decreases, it can make a population more vulnerable to extinction because fewer individuals may possess traits that help them survive new challenges.