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: HIV infects and destroys helper T cells., Fact2: Helper T cells are the critical link in our immune system., Question: What does HIV damage? (A) Leptospirosis (B) immunities (C) Our immune system (D) immunizations (E) Veins and arteries. (F) respiratory system (G) Plant reproduction (H) the body's largest organ
Output:
C