In this subtask, you will answer a simple science question. Please indicate the correct answer. If you're not sure about the answer, choose the last option "I don't know". Do not generate anything else apart from one of the following characters: 'A', 'B, 'C', 'D', 'E'. The "A"-"D" responses correspond to the answer options mentioned in the input. There is a 5th option "E" which should be used for questions for which you're not sure about the answer (e.g., when the questions do not provide enough information to answer).

[Q]: Question: Which of the following enables an animal to get oxygen?  (A) Digestive System (B) Cirulatory System (C) Respiratory System (D) Nervous Syste?
[A]: C.


[Q]: Question: When is a human considered to have reached the adult stage?  (A) When cells no longer divide (B) When the human has begun to talk (C) When the human has begun to walk (D) When most growth has stoppe?
[A]: D.


[Q]: Question: Growing thicker fur in the winter helps some animals to  (A) hide from danger (B) attract a mate (C) find food (D) keep war?
[A]:
D.


