You will be given a definition of a task first, then some input of the task.
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: when a metal rusts , that metal becomes orange on the surface, Fact2: Iron rusts in the presence of oxygen and water., Question: Exposure to oxygen and water can cause iron to (A) decrease strength (B) melt (C) uncontrollable burning (D) thermal expansion (E) turn orange on the surface (F) vibrate (G) Extremes of temperature (H) levitate
Output:
E