In this task, you are given a multiple-choice question and you have to pick the correct option. Answer with option indexes (i.e., "A", "B", "C", and "D").

Example Input: Humans contribute to environmental pollution (A) by purchasing products made from recycled products (B) by switching to energy efficient appliances (C) by leaving behind refuse on public beaches (D) by frequently recycling paper and plastic
Example Output: C

Example Input: An example of an instinctive behavior is (A) doing a cartwheel outside (B) singing on a stage (C) eating a large pizza (D) a mother feeding the kids
Example Output: D

Example Input: Turning beef from red to brown requires energy from (A) heat (B) sound (C) color (D) light
Example Output:
A