In an Experiment on Mutations in Asexual Versus Sexual Yeast

In an experiment on mutations in asexual versus sexual yeast populations, Michael McDonald and colleagues found that

A) deleterious mutations could not be uncoupled from beneficial mutations in asexual populations.
B) only beneficial mutations were accumulated in asexual populations.
C) asexual populations underwent frequent recombination.
D) sexual populations could not uncouple beneficial and deleterious alleles.