When a population evolves rapidly after the introduction of a
new selective pressure (e.g., a pesticide), the alleles involved
(e.g., for pesticide resistance) most typically:
A. result from genetic drift when a random event
(e.g., pesticide application) creates a bottleneck.
B. change in frequency because of migration towards
favorable habitats.
C. result from mutation in response to the new
selective pressure.
D. were present in the population, perhaps at low
frequency, before the new pressure was introduced.