Instructions: 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: burning wood is used to produce heat, Fact2: Air pollution is created by burning., Question: What causes air pollution? (A) Smoking (B) cigarettes (C) producing heat (D) Electrical energy (E) oxygen (F) chemical reaction (G) wind turbines (H) clouds
Output:
C