Simon Is an Avid Gardener Who Spends a Lot of Time

Simon is an avid gardener who spends a lot of time caring for the plants in his garden. To minimize damage from pests from his garden, Simon uses a pesticide spray. After a few years of using the same pesticide spray, he notices that it has become less effective. This is most likely due to

A) evolution by natural selection.
B) using the spray incorrectly.
C) the plants in the garden evolving.
D) the plants maintaining homeostasis.
E) something else in the environment.