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: hydropower requires damming a river, Fact2: Streams and rivers are crossed on rocks, beaver dams, on fallen trees or by wading., Question: Hydropower requires beavers damming what? (A) lakes with large rocks (B) a hydraulic system (C) organisms and their habitat (D) streams with two branches (E) water with old boards (F) scarce resources (G) fissures of hot, acidic water (H) streams with fallen trees
A:
H