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: microorganisms can cause infections, Fact2: Leeches clean away the dead or infected tissue., Question: Dead tissue can be caused by what? (A) disease (B) pollen counts (C) advanced mathematics (D) microorganisms (E) migrating birds (F) viruses (G) Physical weathering (H) harmful substances
Output:
D