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: Active immunity results when an immune response to a pathogen produces memory cells., Fact2: Pathogens are simply a variety of diseases which kill insects., Question: What prevents insects from being killed? (A) Fly swatter (B) Active immunity (C) Exfoliation (D) a cuticle (E) food (F) bugs (G) rays or beams (H) resistance
Output:
B