Which of the following is the only source of new variation in a population?

A) gene flow
B) genetic drift
C) mutation
D) nonrandom reproduction
E) natural selection

Only mutation can create new genetic variation in a population. Gene flow is the movement of genes from one population to another and can introduce existing variation, but it cannot create new variation. Genetic drift and nonrandom reproduction can change the frequency of existing variation, but again, cannot create new variation. Natural selection acts on existing variation but does not create new genetic variation.