Why is a species that has few individuals at greater risk of extinction than a species with a large population size?

A) A species with few individuals is more likely to be eliminated by a reduction in population size caused by a chance environmental event like bad weather or a fire.
B) There's no risk to a small population as long as genetic diversity is high.
C) A species with few individuals is likely to have a high percentage of heterozygotes. This can reduce the likelihood that the species can adaptively evolve in response to environmental changes.
D) Genetic drift allows small populations to avoid the loss of advantageous alleles from the population.