Natural Selection Is One Mechanism to Change Allele Frequency in a Gene

Natural selection is one mechanism to change allele frequency in a gene pool, what is the name of the mechanism that fosters change in allele frequencies due to random chance?

A) Genetic Drift.
B) Natural selection also fosters these changes.
C) Non-Darwinian evolution.
D) Neutral variation.
E) Gene flow from one population to another.