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: Amanda found a wooden box in her grandfather's garage. The top was nailed shut. What type of simple machine should Amanda use to open the box?  (A) lever (B) pulley (C) wheel and axle (D) inclined plan?
Example Output: A.

Example Input: Question: A marble is dropped in a glass of water. Which force pulls the marble to the bottom of the glass?  (A) electricity (B) friction (C) gravity (D) magnetism?
Example Output: C.

Example Input: Question: Why do some animals have claws, spines, shells, or give off a smell?  (A) migration (B) hibernation (C) seasonal change (D) defense mechanis?
Example Output:
D.