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: All chemical reactions require activation energy to get started., Fact2: Chemical changes are a result of chemical reactions., Question: What is required before a chemical change? (A) kinetic energy (B) energy usage (C) activation push (D) activation energy (E) activation switch (F) activation power (G) Burning fuel and air (H) Evaporation
D

Fact1: Air pollution harms the respiratory and circulatory systems., Fact2: Cars are a significant source of air pollution., Question: What harms the respiratory and circulatory systems? (A) oil (B) rain (C) sulfur (D) cars (E) tires (F) coal (G) tar (H) bicycles
D

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

D