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: Which of the following is an example of a chemical change?  (A) clouds forming (B) sugar dissolving (C) water freezing (D) a candle burnin?
Example Output: D.

Example Input: Question: Water freezing is an example of a  (A) liquid changing to a solid (B) solid changing to a liquid (C) gas changing to a solid (D) gas changing to a liqui?
Example Output: A.

Example Input: Question: How can we change the chemical compositon of iron?  (A) cause it to rust (B) cause it to melt (C) cut it into pieces (D) expose it to a magne?
Example Output:
A.

