how does natural selection affect allele frequencies? it increases the frequency of all new alleles. it…

Brief Explanations:

Natural selection favors traits that increase an organism's fitness. Beneficial alleles contribute to higher fitness and thus become more common over time. Detrimental alleles reduce fitness and become less common. Not all new alleles are beneficial, so their frequency isn't always increased. Also, natural - selection doesn't eliminate all new mutations as some may be neutral or beneficial.

Answer:

B. It causes detrimental alleles to become less common. C. It causes beneficial alleles to become more common.