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: hearing is used for sensing sound by animals, Fact2: An ear improves hearing., Question: What does an ear improve? (A) activation energy (B) Relieve pain (C) Sensing sound (D) looseness (E) vision (F) Sensing wavelengths (G) nervous system (H) sight
C