Passage Summary: Peter argues that farmers can protect their crops from insects by keeping the plants slightly underwatered, as this makes the leaves too tough for bugs to enjoy.

Conclusion: Farmers should water crops only enough to avoid substantial threats to growth or yield in order to minimize damage.

Reasoning: Insects prefer the softer leaves of abundantly watered plants over the tougher leaves of mildly drought-stressed plants.

Analysis: To strengthen Peter's argument, we need to ensure that his 'tough leaf' strategy doesn't have hidden costs that outweigh the benefits of insect resistance. Peter assumes that the 'mild drought stress' he recommends won't attract other problems or cause damage that is worse than the insect damage he is trying to prevent. Look for an answer choice that confirms this strategy is effective or that it doesn't inadvertently lead to other types of crop failure. We want to bridge the gap between 'bugs like water' and 'farmers should therefore withhold water.'