Conclusion: Capsaicin in the chili pepper garden kept the raccoons at bay.
Reasoning: Capsaicin, a chemical present in most chili peppers, is used in sprays engineered to repel raccoons
We need to strengthen the above argument i.e. above conclusion while employing the use of reasoning.
A. Capsaicin can be found in many foods, but in lower concentrations than within the peppers themselves.
Incorrect. Totally irrelevant. We are concerned with Capsaicin present in Chilli Peppers and its effects on Raccoons.We don't know if the Campground had other foods around it.
B. The raccoon population had been reduced that season by an outbreak of a lethal virus endemic to the area.
This is a weakener and suggests an alternate reason for the lack of raccoons. Eliminated.
C. An unusually late frost destroyed a part of the chili pepper garden a month into spring.
Irrelevant. We are not concerned with more or less Capsaicin (as a result of more or less CP) but rather its effect on racoons. Eliminated.
D. A type of squirrel, notably resistant to capsaicin, was found in abundance throughout the campground.
Correct. This answer choice closes the weakness in the argument that there could have been some other reason too by drawing a comparison between Capsaicin resistant animals such as Squirrel which were found in abundance vis-a-vis Raccoons which are repelled by Capsaicin.
E. Another chemical, found in onions, is also repellant to raccoons.
Incorrect. Same as B. We don't know if there are other foods around the campground.