An isolated population of great purple hairstreaks, a species of butterfly, lives in a damp meadow. The larvae feed only on a species of mountain clover plant that lives in the meadow. The adult does not fly far from the clover plants as well. One rainy summer, a fungus causes most of the clover plants to die. A scientist hypothesizes that, with a diminished supply of clover, not as many larvae will survive to become butterflies. To test this hypothesis, he sets up a camera to observe the larvae as they develop. Surprisingly, the number of butterflies that emerged from cocoons that summer was very close in number to those that populated the meadow the previous summer. After obtaining this result, the scientist decided he must have done something wrong. A better way to test the impact of clover on the butterflies is to A) isolate a sample of the butterflies and split them into groups, exposing them to different amounts of clover. B) exterminate all the clover in the meadow, and use the camera to observe the impact on the butterfly population. C) isolate a sample of the butterflies and observe them, exposing them to about the same amount of clover that is in the meadow, but under controlled conditions. D) find out if the fungus also somehow affected the dragonfly population, which are the butterflies chief predators, in case this led to the higher than expected larvae survival rate.