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 reading on a barometer rises when the air  (A) pressure increases. (B) pressure decreases. (C) speed increases. (D) speed decreases?
Example Output: A.

Example Input: Question: The movement of soil by wind or water is called  (A) condensation (B) evaporation (C) erosion (D) friction?
Example Output: C.

Example Input: Question: A student puts two identical plants in the same type and amount of soil. She gives them the same amount of water. She puts one of these plants near a sunny window and the other in a dark room. This experiment tests how the plants respond to  (A) light (B) air (C) water (D) soil?
Example Output:
A.