You are given a science question (hard-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.

Example Input: Of these research projects, which is the best choice for a student who is interested in environmental issues to study?  
 (A) making cars run on less fuel (B) finding more sites for copper mines (C) making ocean liners bigger and faster (D) replacing human workers with robots
Example Output: A

Example Input: Thomas Edison most likely invented the light bulb by using  
 (A) lit candles. (B) atomic models. (C) reflected light. (D) the scientific method.
Example Output: D

Example Input: Which is most likely responsible for the chinch bugs' ability to survive repeated exposure to insecticides?  
 (A) species diversity (B) genetic diversity (C) ecosystem diversity (D) population diversity
Example Output:
B