You are given a science question (easy-level) and four answer options (associated with "A", "B", "C", "D"). Your task is to find the correct answer based on scientific facts, knowledge, and reasoning. Do not generate anything else apart from one of the following characters: 'A', 'B, 'C', 'D'. There is only one correct answer for each question.
Q: By inserting a gene into crop plants, scientists have developed plants that are resistant to insects. If an insect eats the plant, the insect dies. Which practice is unnecessary with this new plant variety?
(A) eroding the land by tilling (B) overproducing food crops (C) removing weeds from crops (D) spraying plants with pesticides
A:
D