A Selection-Mutation Balance Occurs When

Multiple Choice

A selection-mutation balance occurs when

A) mutation introduces alleles that selection favors for one reason, even if the alleles also cause a trait that is deleterious.
B) mutation introduces deleterious recessive alleles at a rate that is similar to or higher than the rate at which selection removes the alleles.
C) a large number of deleterious mutations occur over a short period of time, and there is no subsequent selection against them.
D) a beneficial mutation arises and spreads for a specific period of time, then the mutation becomes deleterious in a new environment and is removed by selection over a similar period of time.