Instructions: 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").
Input: A person fills their tank with fossil fuels, and knows that in one hundred years (A) they may be more bountiful (B) they may be more frequent (C) they may cease existing (D) they may be free
Output:
C