Passage Summary: A specific caterpillar eats only one type of fruit that lacks a specific acid. This acid is needed to make a chemical called volicitin, and this caterpillar happens to lack that chemical.

Reasoning: H. subflexa caterpillars eat only Physalis fruit, which lacks linolenic acid; linolenic acid is required to produce volicitin, and H. subflexa lacks volicitin.

Analysis: Since this is a Must Be True question, we need to find a statement that is strictly supported by the combination of these facts. We are told that linolenic acid is a necessary ingredient for volicitin and that the caterpillar's exclusive food source lacks this acid. It follows logically that the caterpillar's lack of volicitin is likely due to the absence of that specific acid in its diet. Look for an answer choice that draws this direct connection between the dietary deficiency and the absence of the chemical.