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: if a chemical reaction occurs, it might have been triggered by which of these? (A) a person yelling at it (B) a person walking by it (C) a person looking at it intently (D) a person cranking up the room heater
Example Output: D

Example Input: the presence of which of these is required for the formation of cavernous chambers? (A) some carbonated soda (B) some carbon dioxide (C) some carbonic acid (D) carbon monoxide gas
Example Output: C

Example Input: A source of heat at the resort is the (A) jacuzzi (B) pool (C) chair (D) umbrella
Example Output:
A