Instructions: 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: Oxygen is essential for cellular respiration for all aerobic organisms., Fact2: Arteries carry oxygen to tissues and organs., Question: What are essential for cellular respiration? (A) leaves (B) Energy (C) arteries (D) Energy. (E) branches (F) glucose (G) acetic acid (H) skull
Output:
C