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 prism is used for refracting light, Fact2: Refraction is the bending of light cause by a speed change when it passes through different media., Question: What aspect of light changes when it passes from air into a prism? (A) power (B) seasons (C) speed (D) energy (E) a wave (F) Joules (G) heat (H) unique
Output:
C