- A. Farmers can use caterpillars to feed on weeds in their crop fields/plantations.
- B. This finding can help in the development of clinically useful antimicrobial compounds.
- C. This finding can help in the development of organic, ecologically sustainable pesticides.
- D. Caterpillars can be genetically modified to be predators of the other plant pests.
Answer: C
Explanation
The passage describes how caterpillars use their frass to suppress plant defenses against insect predators, and notes that this discovery ‘could throw new light on compounds associated with plant response to pathogens.’ The most logical and practical application of understanding how a natural compound (frass) manipulates plant defenses is in developing new, environmentally friendly methods for pest control. This aligns with option (C), suggesting the development of organic, ecologically sustainable pesticides. Option (A) is irrelevant as the passage discusses corn, not weeds. Option (B) is too broad; the focus is on plant response, not general antimicrobial compounds. Option (D) introduces genetic modification, which is not mentioned or implied in the passage. This question requires identifying the most plausible practical implication of a scientific discovery described.