Given the task definition and input, reply with output. 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: drought is when amount of precipitation decreases, Fact2: Drought causes famine, which contributes to decentralization and unrest., Question: What can cause famine? (A) Movement of an air mass (B) Effective fertilizers (C) the ground shaking (D) Increased irrigation (E) Crop harvesting (F) Decreased precipitation (G) single-celled organisms (H) forest is destroyed
F