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).

Q: Question: What is the source of energy required to begin photosynthesis?  (A) Sunlight (B) Water (C) Starch (D) Chlorophyl?

A: A.
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Q: Question: A student perfoms an experiment by feeding two mice different amounts of food for a week. At the end of the week, she weighs the two mice. Weighing the mice is an example of  (A) a measurement (B) a hypothesis (C) an explanation (D) background researc?

A: A.
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Q: Question: The movement of the Earth in its orbit around the Sun is the Earth's ___.  (A) rotation (B) revolution (C) evolution (D) til?

A:
B.
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