What is the frequency of an allele if it is evolutionarily successful?

Explanation

An evolutionarily successful allele tends to increase in frequency within a population because it confers a survival or reproductive advantage. Natural selection favours such alleles, leading to a greater likelihood that individuals carrying them will survive and reproduce, passing these advantageous alleles to their offspring. Over multiple generations, this process results in an increased presence of the allele in the population. On the other hand, alleles that do not provide such advantages are less likely to be passed on or may even decrease in frequency if they are disadvantageous. Thus, Option A is correct, while Options B, C, and D do not accurately capture the dynamics of an evolutionarily successful allele.