In a Population That Is Polymorphic for Sexual/asexual Reproduction, a Sexually

In a population that is polymorphic for sexual/asexual reproduction, a sexually transmitted disease has just eliminated most of the sexually reproducing individuals. When you expose samples of asexuals and sexuals from this population to harsh environmental conditions in the lab, you discover that the sexual individuals are worse at adapting to the new environment than the asexual individuals. (Note that your lab population is free from the sexually transmitted disease.) Which of the following statements is a likely explanation for your results?

A) All asexually reproducing strains independently acquired the same beneficial mutation that offset the advantage of the sexuals.
B) The bottleneck caused by the disease resulted in the fixation of many alleles in the sexually reproducing population.
C) Asexuals are favored under harsh environmental conditions.
D) The results support standard evolutionary theory.