Explanation

Since Tess was worried about the pesticides’ noxious effects, a word like small or minimal would make sense in the blank. Both capacious and profuse are nearly the opposite of what you’re looking for, so eliminate choices (A) and (F).

Choices (B) and (D) give equivalent meanings as well, but lasting effects are what Tess is trying to avoid. Both nominal and negligible can mean small, so choices (C) and (E) give you appropriate, equivalent sentences.

Hence options C and E are correct!