Given the task definition and input, reply with output. 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").

Fact1: a prism is used for refracting light, Fact2: Light contains energy., Question: What is used for refracting energy? (A) wind (B) a circuit (C) a prism (D) Decibels (E) a window (F) glass (G) a doorbell (H) a wave
C