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 compass is used to navigate oceans, Fact2: Ocean waves travel on the surface of the water., Question: A compass is used to travel on the surface of what? (A) planes (B) water (C) stars (D) boats (E) marine (F) clouds (G) poles (H) sun
Output:
B