Definition: In this task, you are given two facts, and a multiple-choice question. Based on the given facts, answer the question with index of the correct option (e.g, "A").
Input: Fact1: a breathing mask is used for keeping harmful particles from entering the respiratory system, Fact2: Unlike larger particles, the smaller particles are able to enter the respiratory system., Question: A breathing mask can prevent what kind of particle from entering the lung? (A) light (B) harmful (C) rabies (D) A virus (E) x-ray (F) deadly (G) ion (H) small
Output:
H