In this task, you're given an open-domain question. Your task is to provide an answer to the given question. There is only one unique answer for each question. Your answer should be short, and refer to an entity, date, number, etc. Do not put your answer in the context of a sentence.

Q: When was the last solar eclipse seen in pa?

A: 1838 Sep 18 (Annular)
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Q: What was the point of the skinner box?

A: perform studies in conditioning and training
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Q: The molecule that acts as the final electron acceptor of the electron transport chain is?

A:
molecular oxygen
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