Definition: 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").
Input: Fact1: All life relies on a relatively narrow range of pH, or acidity., Fact2: Life during most of the Precambrian was restricted to bacteria and algae., Question: Bacteria relies on a relatively narrow range of what? (A) RNA (B) Fe (C) 12 (D) DDT (E) DNA (F) pH (G) CO2 (H) O2
Output:
F