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: Prism A prism is a solid geometric shape., Question: What can refract light? (A) focusing a lens (B) Electrical energy (C) solid geometric shapes (D) an electron lens (E) Something formed from skeleton (F) single-celled organisms (G) living things (H) an electron microscope
Output:
C