题目

Some people will do just about anything to save money．And I am one of them．Take my family's last vacation．It was my six﹣year﹣old son's winter break from school，and we were heading home from Fort Lauderdale after a weeklong trip．The flight was overbooked，and Delta，the airline，offered us 400perpersonincreditstogiveupourseatsandleavethenextday．IhadmeetingsinNewYork，soIhadtogetback．Butthatdidn'tmeanmyhusbandandmysoncouldn'tstay．Itookmynine﹣month﹣oldandtookoffforhome．Thenextday，myhusbandandsonwereofferedmorecreditstotakeanevenlaterflight．Yes，Iencouraged现已建成的核电站利用的是(　) A．放射性元素衰变放出的能量 B．人工放射性同位素放出的能量 C．重核裂变放出的能量 D．轻核聚变放出的能量