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: When liquid water freezes, it forms ice. What is the physical state of an ice cube?  (A) gas (B) solid (C) liquid (D) plasm?
Example Output: B.

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: Ice cream in a bowl changed from solid to liquid in a few minutes. Which of the following most likely caused this change?  (A) Bacteria grew in the ice cream. (B) Heat was added to the ice cream. (C) Water evaporated from the ice cream. (D) Frozen berries were sprinkled on the ice cream?
Example Output:
B.