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).

Example Input: Question: The systems of the human body work together. Which system works with the skeletal system by pulling on the bones to create movement?  (A) digestive (B) circulatory (C) muscular (D) nervou?
Example Output: C.

Example Input: Question: A caterpillar is relying on a producer as a source of food. Which of the following is a producer that a caterpillar would most likely use?  (A) leaves on a tree (B) cocoons (C) birds in a nest (D) sunlight in the sk?
Example Output: A.

Example Input: Question: If humans cut down too many trees in a forest, there may be more  (A) forest animals (B) floods (C) food (D) tree?
Example Output:
B.