Detailed Instructions: 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: contact between rocks over long periods of time causes rocks to smooth, Fact2: Rocks are actually solid mineral deposits., Question: Contact between solid mineral deposits over long periods of what causes them to smooth (A) time (B) vacuum (C) widen (D) cracks (E) clocks (F) years (G) Bend (H) instant
A:
A