<u>Answer:</u>
The correct answer option is: frequency of the recessive allele.
<u>Explanation:</u>
When there are no mutations, no selective forces, no gene flow, no non-random mating and large population size, the population is said to be in Hardy- Weinberg equilibrium.
When Hardy-Weinberg equilibrium is met, it is written in the form of an equation which is as follows:

where
represents the frequency of the homozygous dominant allele,
is the frequency of the heterozygous allele while q or
represents the frequency of the homozygous recessive allele.
Natural Factors:
Ocean Currents, Distance of the Sea, Wind Directions, Topography, Your country's distance from the equator , Volcanic Eruptions, The sun, and especially humans.