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: most canyons are formed by flowing rivers through erosion over long periods of time, Fact2: Canyon Lake Canyon lake was formed by dams on the Salt River., Question: what can form canyons? (A) spring (B) storms (C) dams (D) mines (E) salmon (F) two (G) rain (H) cut
A:
C