What Is Meant by Adaptation from Standing Genetic Variation in Natural

Multiple Choice

What is meant by adaptation from standing genetic variation in natural populations?

A) A population adapts to an environmental change by the occurrence of a beneficial mutation in an individual that introduces genetic variation, which rises to high frequency in the population because it is favored by natural selection following the environmental change.
B) A population adapts to an environmental change by the rise to high frequency of an existing genetic variant that was already present in the population at low frequency before the environmental change.
C) Individuals with more variation present in their genomes are favored by natural selection following an environmental change, and the population adapts via an overall increase in genetic variation in the population because the most genetically variable individuals have highest fitness.
D) Genetic variation becomes costly for individuals following an environmental change, and the result is that overall genetic variation in a population decreases as the population adapts to the environmental change.