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 likely to cause the most erosion?  (A) a river (B) a small creek (C) a pond (D) a puddl?
Example Output: A.

Example Input: Question: Tobias rode his bike on a road for a 2 hr period. On average, he passed a 1 km marker every 3 min during this period. Which of the following was his average speed for this 2 hr period?  (A) 10 km/hr (B) 15 km/hr (C) 20 km/hr (D) 25 km/h?
Example Output: C.

Example Input: Question: Freezing of any substance occurs ___.  (A) when the particles of the substance are able to slide past one another (B) at 0Â°C (C) when a liquid changes to a solid, regardless of temperature (D) when energy is added to a substanc?
Example Output:
C.