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").
Input: Fact1: treating water is used to remove harmful substances before drinking, Fact2: To ensure that it is safe to drink water, treat it all the time., Question: To ensure that water is safe to drink, harmful what are removed before drinking? (A) leeches (B) seeds (C) toxins (D) currents (E) bacteria (F) substances (G) Roundworms (H) plants
Output:
F