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: rocks interacting with wind over long periods of time causes weathering, Fact2: Weathered rock is called saprolite ., Question: Saprolite is created when what interacts with wind over long periods of time? (A) soils (B) trees (C) rocks (D) water (E) erosion (F) calcite (G) heat (H) oil
C