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 an iron nail wrapped in a copper wire is attached to a circuit, it forms  (A) a battery. (B) an engine. (C) an insulator. (D) an electromagnet?
Example Output: D.

Example Input: Question: Which feature is a physical property of copper?  (A) insulates heat (B) conducts electricity (C) strong magnetic force (D) liquid at room temperatur?
Example Output: B.

Example Input: Question: A student wants to look under a heavy rock. Which simple machine would be BEST to use to lift the rock?  (A) Wheel and axle (B) Lever (C) Inclined plane (D) Scre?
Example Output:
B.