Given the task definition and input, reply with output. 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: a greenhouse is used to protect plants by keeping them warm, Fact2: Another well known plant is the Mesquite Bush., Question: What can a greenhouse protect by keeping warm? (A) mussels (B) Species (C) organisms (D) lights (E) bushes (F) rocks (G) Oak (H) hats
E