Hypothetical population gene pool problem

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Hypothetical population gene pool problem

In a hypothetical population’s gene pool, an autosomal gene, which had previously been fixed, undergoes a mutation that introduces a new allele, one inherited according to incomplete dominance. Natural selection then causes stabilizing selection at this locus. Consequently, what should happen over the course of many generations?
a. The proportions of both types of homozygote should decrease.
b. The proportion of the population that is heterozygous at this locus should remain constant.
c. The population’s average heterozygosity should decrease.
d. The two homozygotes should decrease at different rates.