For a trait to afffect natural selection it must be what

Natural selection works on populations with a variation in traits, such as coloring. Its main premise is that when there is a trait that allows one individual to better survive in an environment than another, the former is more likely to reproduce.How does natural selection affect traits?

Four conditions are needed for natural selection to occur: reproduction, heredity, variation in fitness or organisms, variation in individual characters among members of the population. If they are met, natural selection automatically results.

Explanation:

stress fractures occur largely in the feet and legs and are common in sports that require repetitive impact, primarily running/jumping sports such as gymnastics or track and field.

answer; i believe its echoic memory,it is believed to last three to four seconds; good luck