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题目材料：
Prolonged and unseasonable frosts produce frost rings in deciduous trees that grow in moderate climates. Frost rings do not appear in any of the fossilized deciduous trees that have been found in Antarctica. Hence, it is unlikely that such frosts occurred in Antarctica at the time these fossilized trees were alive.
Which of the following is an assumption on which the argument depends?
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AExtreme frost events occur less frequently today than they did in ancient times.
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BFrost rings cannot develop in a deciduous tree after it has died.
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CThe process of fossilization does not completely obscure frost rings in deciduous trees.
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DOnly a small fraction of deciduous trees from ancient Antarctica were preserved as fossils.
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EDeciduous tree species that lived in ancient Antarctica were very different from the modern ones.
C显示答案
