题目内容：
根据以上材料和以下选项请回答题：
A．Nuclear Reactions as the Lasting Source of the Sun’s Energy
B．The Most Important Source of Energy
C．Types of Electromagnetic Energy
D．X-rays Are Used to Detect and Treat Cancer．
E．Seeking New Sources of Energy
F．Nuclear Energy is Beginning to Compete with Coal
Paragraph2 __________.
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答案解析：