Tail length in mice varies within a population. Scientists observed change in the distribution of tail lengths in a mouse population over time. At the genetic level, what has most likely happened to the allele for the shortest tail lengths?

A The allele changed from being dominant to being recessive.
B The allele changed from being autosomal to being sex-linked.
C The allele became less frequent than the alleles for longer tail lengths.
D The allele began to code for long tail lengths instead of the shortest ones.