Final answer:
B. Genetic drift is the process by which allele frequencies in a small population are altered due to random chance events, not by conferring any survival advantages.
Step-by-step explanation:
The process by which allele frequencies are altered in a small population due to chance is called genetic drift. Genetic drift can occur because of random events that affect an individual's ability to survive and reproduce. A classic example of this is if an individual with unique alleles dies before reproducing simply due to chance, like being preyed upon unexpectedly or failing to find a mate. It plays a significant role in small populations and is illustrated by events such as the founder effect.
This can lead to a change in the genetic makeup of the population, purely by accident and not because the alleles confer any survival advantage. In small populations, these changes can be quite significant because each individual represents a larger portion of the gene pool compared to large populations. The founder effect is a special case of genetic drift that occurs when a new population is started by a small group of individuals, and it can result in a population that has different allele frequencies than the original population from which it was derived.