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: an animal usually requires a warm body temperature for survival, Fact2: Mammals are also warm-blooded and are covered with hair or fur., Question: What helps maintain body temperature? (A) hats (B) Lift (C) the inside of a refrigerator (D) fur (E) skin (F) arctic winds (G) freezing water (H) hair
[A]: D


[Q]: Fact1: Echinoderms lack a centralized nervous system., Fact2: Sand dollars and sea biscuits are also echinoderms., Question: What lacks a centralized nervous system? (A) Damaged hearing (B) Humans (C) Horses (D) Sand dollars (E) insects (F) Chickens (G) Pesticides (H) barnacles
[A]: D


[Q]: Fact1: Mollusks have a circulatory system with one or two hearts that pump blood., Fact2: Mollusks have a simple heart, which pumps the blood throughout the body., Question: What do mollusks hearts circulate through the body? (A) liquid (B) Energy (C) complex (D) food (E) water (F) blood (G) grass (H) oxygen
[A]:
F