Which factor do biologists calculate when they determine whether a population is in hardy-weinberg equilibrium?
mutation rate
genotype frequencies
number of phenotypes
rate of migration

The correct answer is-

genotype frequencies.

Hardy-Weinberg equilibrium is a condition according to which frequency of gene variant in the population of sexually reproducing individuals remains constant over generations ( that is it does not change from one generation to another generation).

There is an equation for the Hardy Weinberg law, which helps in determining the genotypes ( such as frequency of homozygous dominant, heterozygous domiant, and homozygous recessive genotypes). The equation is-

Where p² represents the homozygous dominant, 2pq represents heterozygous domiant, and q² for homozygous recessive genotypes.

i think a) betsy can donate only blood to mark is correct because, mark and betsy have the same blood type. whereas nobody else has b+ blood so betsy can't donate to them.

a physical change is being made.