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: a valley is formed by a river flowing, Fact2: Examples are Napa Valley and Sonoma Valley., Question: what were formed by a river flowing? (A) Statue of Liberty (B) body water (C) swamp vegetation (D) Rockies (E) Napa and Sonoma (F) clouds (G) Sediment (H) Calcium carbonate
E