You are given a science question (easy-level) and four answer options (associated with "A", "B", "C", "D"). Your task is to find the correct answer based on scientific facts, knowledge, and reasoning. Do not generate anything else apart from one of the following characters: 'A', 'B, 'C', 'D'. There is only one correct answer for each question.

Q: What gas in the air do we need to breathe in order to live?  
 (A) nitrogen (B) oxygen (C) carbon dioxide (D) hydrogen (E) water vapor

A: B
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Q: All of the following can become fossils except  
 (A) bones. (B) shells. (C) teeth. (D) rocks.

A: D
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Q: The life cycle of a star includes formation, life, and death. In the Universe, where do new stars originate?  
 (A) from fusion in red giants (B) in molecular clouds of gas (C) in radiation from black holes (D) from large fragments of antimatter

A:
B
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