If a Certain Allele Is Quite Common in a Human

If a certain allele is quite common in a human population, what is likely the result?

A) Traits related to that allele will also be quite common.
B) People in the population will all look similar.
C) The population will tend to shrink due to lack of diversity.
D) The people will be inbred.
E) That allele will eventually become dominant.