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: Fact1: a plant requires sunlight to grow, Fact2: Plants to avoid are fast-growing vines that can take over an area in no time., Question: What requires sunlight in order to take over an area? (A) spores (B) fish (C) plants (D) humans (E) pods (F) Oak (G) opossums (H) coral
Example solution: C
Example explanation: This is a good example. Based on the facts plants require sunlight in order to take over an area.

Problem: Fact1: a greenhouse is used to protect plants by keeping them warm, Fact2: Plants are Earth's producers., Question: What is used to protect producers and keep them warm? (A) an electric stove (B) sweaters (C) green houses (D) dirt (E) animal fur (F) In the winter (G) evaporation (H) plant fans

Solution: C