Definition: 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: Water vapor cooling (A) will thoroughly evaporate into the air (B) will quickly become ice (C) becomes steam in the atmosphere (D) becomes droplets of h2o on a boiling pot's lid
Output:
D