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").
Q: Fact1: staying warm has a positive impact on an animal 's survival, Fact2: Man is an animal with primary instincts of survival., Question: What has a positive impact on mans survival? (A) food (B) support (C) heat (D) warmth (E) bamboo (F) warm (G) glycogen (H) hormones
A:
D