$(p+q{)}^2=p^2+2pq+q^2=1$ represents an equation used in:

The correct option is B population genetics
Population genetics:

$(p+q{)}^2=p^2+2pq+q^2=1$

The equation is known as Hardy-Weinberg principle in which

● p is the frequency of dominant allele

● q is the frequency of recessive allele

The equation is used in population genetics.

This equation is applicable in a population where the following exist:-

● There is no natural selection

● Mating among organisms is random and

● Migration is absent. In this case the population is said to be in genetic equilibrium

Final answer:

a. Population genetics