Detailed 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").
Q: Fact1: Lung cancer is most often caused by exposure to tobacco smoke., Fact2: Tobacco smoke contains tar., Question: Lung cancer is most often caused by exposure to (A) DDT (B) UV (C) methane (D) tar (E) CFCs (F) vapor (G) SO2 (H) carbon dioxide
A:
D