In the sentence, certain words are in bold and numbered from A to E, which are the possible pairs to be interchanged. Choose the pair(s) of words which need to be interchanged to make the sentence grammatically correct and meaningful.

The (A) enemies of using pests’ natural (B) method  is (C) known as biological control, and is (D) considered an eco-friendly (E) alternative to the use of insecticides.