instruction:
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).
question:
Question: The main function of the heart is to ___.  (A) pump blood (B) remove wastes (C) produce arteries (D) collect oxyge?
answer:
A.


question:
Question: A see-saw is an example of which type of simple machine?  (A) lever (B) pulley (C) wheel (D) inclined plan?
answer:
A.


question:
Question: The continuous changes of a seed to an adult plant that produces seeds is known as a  (A) lunar cycle. (B) weekly cycle. (C) daily cycle. (D) life cycle?
answer:

D.