Which of the following is most likely to create genetic variation in a population?

a
RNA polymerase errors during transcription
b
Helicase failure to unwind DNA during replication
c
DNA polymerase errors during replication
d
Misincorporation of amnio acids by tRNA during translation

D

Explanation:

Genetic variation can be created by random mating, random fertilization, and recombination between homologous chromosomes during meiosis. I think b and c can be ruled out because they are relatively unlikely in themselves. D seems to be most likely due to RNA splicing and other methods that occur to avoid those errors.