The major effect of genetic drift is..
A) a reduction in genetic variability.
B) an increase in genetic variation to accommodate changes in abiotic conditions.
C) no change in population size but an increase in favorable alleles.
D) a reduction in population size and an increase in genetic variability.
Genetic drift results in a reduction in genetic variability. Depending on the situation, there may be a reduction or increase in the population. So, the answer is A.
