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").

Example Input: Fact1: Active immunity results when an immune response to a pathogen produces memory cells., Fact2: Vaccination is Active Acquired Immunity., Question: What results when an immune response to a pathogen produces memory cells? (A) anemia (B) vaccination (C) kill them (D) competition (E) lie detectors (F) rapid expansion (G) killing insects (H) it needs them
Example Output: B

Example Input: Fact1: Flowing water can slowly dissolve carbon in sedimentary rock., Fact2: Rivers and streams are bodies of fresh, flowing water., Question: What can slowly dissolve carbon in sedimentary rock? (A) hydrocarbons (B) acetic acid (C) precipitation (D) evaporation (E) rivers and streams (F) puddles (G) ponds (H) nitrogen
Example Output: E

Example Input: Fact1: Mammals conserve body heat with their hair or fur., Fact2: Body heat is trapped in the haircoat., Question: What do mammals use to conserve heat? (A) energy (B) Energy. (C) fur and fat (D) blood (E) haircoat (F) food (G) body water (H) tail
Example Output:
E