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").
Q: Fact1: smoking causes direct damage to the lungs, Fact2: Mammals are warm blooded, use lungs for respiration, and have four legs., Question: What harms the respiration system? (A) Pollution (B) sweating (C) Pesticides (D) exercise (E) smoking (F) parasites (G) swimming (H) breathing
A:
E