Genetic drift
a. is a predictable event
b. increases genetic differences between populations
c. happens when random events change the genotype of a population
d. happens when well-adapted organisms survive and reproduce more often than poorly-adapted organisms

Genetic drift happens when well-adapted organisms survive and reproduce more often than poorly-adapted organisms. The statement that best sums up evolution is the change in a population through genetic variation over time. Natural selection may be through (1) differential reproduction, that is, not all organisms are able to reproduce to their fullest capacity because nature cannot simply sustain it and (2) acquire genes, that is heredity.