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").

Ex 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

Ex Output:
C

Ex Input:
Fact1: a black hole is formed by a high-mass star collapses, Fact2: Black Holes Black holes are the inevitable conclusion of Einstein's General Theory of Relativity., Question: When do stars fulfill the inevitable conclusion of Einstein's General Theory of Relativity? (A) inactive (B) Winter (C) an object (D) observe it (E) collapse (F) light (G) our star (H) ligt

Ex Output:
E

Ex Input:
Fact1: the digestive system breaks food into nutrients for the body, Fact2: Catabolism is the breaking down of food., Question: what does the digestive system use to produce nutrients for the body? (A) Proteins (B) Enzymes (C) oysters (D) catabolism (E) lungs (F) ice cubes (G) hair (H) nutrients

Ex Output:
D