The energy（）by the nuclear reaction is transformed into heat.

The energy（）by the nuclear reaction is transformed into heat.
A、relieved
B、freed
C、loosened
D、released
【正确答案】：D
【题目解析】：本题考查分词作定语。relieved 减轻 解除; freed 释放的，多用于人; loosened 松开 放开; released 释放。和句中的主语“energy”最适合搭配的动词是D选项。句意：核反应释放的能量转化为热能。