The Following Graphs Show the Frequency of the B+ Allele

Multiple Choice

The following graphs show the frequency of the b+ allele over 20 generations in two populations of heterozygous flour beetles (data for a population of 10 individuals is shown in graph A; data for a population of 100 individuals is shown in graph B) . Why does the frequency of the b+ allele increase in both populations?

A) b+ is a lethal allele.
B) b+ is a balanced polymorphism.
C) b+ is a fixed allele.
D) b+ allele is adaptive.
E) b+ is a neutral mutation.