In eastern gray squirrels, Sciurus carolinensis, the allele for black fur (B) is dominant to the allele for gray fur (b) . In a particular population of gray squirrels, 64% have black fur and 36% have gray fur. A researcher calculated the allelic frequencies to be B = 0.6 and b = 0.4. Which of the following could best explain the increase in the frequency of the Ballele in the population after five years? a. The frequency of the B allele increased because it is the dominant allele.
b. The frequency of the Ballele increased because squirrels with gray fur exhibited greater fitness.
c. The frequency of the B allele increased due to the selective pressures of the environment.
d. The frequency of the Ballele increased because black squirrels randomly mate with other eastern gray squirrels.

The answer to the given question is C.

Explanation:

Natural selection:

The population contains both superior as well as inferior organisms where natural resources are limiting so it will cause competition between organisms. As a result of competition, it will select superiors, and inferiors are deleted and they are given reproductive advantages. Due to this reproductive advantage new population emerges. It is more suitable for the environment.  

Natural selection divides into three parts that are directional, disruptive, and stabilizing selection.  

This is an example of natural selection. Environmental conditions create pressure on the individuals and if they can survive and become fittest, their number increases in the population. This is according to Darwin's theory in the struggle for existence. These organisms survived as the fittest organisms to match climatic conditions.

Stabilizing selection: This operates when features coincide with the optimal environmental conditions and the organisms survive in a population. Stabilizing selection pressures do not promote evolutionary change but tend to maintain stability within the population from generation to generation.  

In the beginning, directional selection - the organism develops characters to survive in response to gradual changes in the environmental conditions. It works on a range of phenotypes existing within a population and exerts selection pressure which moves the mean phenotype to one phenotypic extreme. When the mean phenotype overlaps with the new optimum environmental conditions, stabilizing selection will take over.  

this is math not biology xd