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: Max mixed some orange flavored powder in a glass of water until there it was dissolved. His sister tasted it and it tasted like (A) cola (B) dark chocolate milk (C) a citrus fruit (D) lemons and apples
Example Output: C

Example Input: the alps were formed by rock what? (A) growing (B) melting (C) erupting (D) creasing
Example Output: D

Example Input: What is the source of air? (A) humans (B) space (C) chemistry (D) nature
Example Output:
D