The proposition in the argument that farmers have to use greater and greater amounts of costly insecticides to control insect pests is not an intermediary conclusion, it is merely an assertion used to support the main conclusion.
Furthermore, even if you were to take it to be an intermediary conclusion, none of the other answer choices make sense in context.
(A) is not correct because that statement is not the main conclusion. The main conclusion is that in the long run, it is counterproductive for farmers to use insecticides.
(C) is wrong because again it is not the actual conclusion of the argument.
(D) is wrong because the statement does not support anything other than the main conclusion, whereas (D) states that it is being used to support the intermediary conclusion that directly supports the main conclusion.
(E) is wrong because the argument's conclusion does not offer a causal explanation for the identified statement.
The proposition is merely a claim or an assertion that has a causal explanation (cause: insects resistance to insecticides increases with insecticide use. effect: farmers have to use greater and greater amounts of costly insecticides to control insect pests.), which is used to directly support the argument's main and only conclusion.
Hope that clears things up! Please let us know if you have any other questions.
Brett-LindsaySeptember 30, 2020
I (and the teacher who wrote the explanations) also took it to be an intermediate conclusion.
