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: blowing air into a whistle causes air to vibrate inside the whistle, Fact2: All sounds begin with vibrations., Question: what do whistles use to make sound? (A) Collagen (B) air (C) Energy. (D) power (E) oxygen (F) waves (G) friction (H) energy
Output:
E