参考答案和解析
正确答案:
A
解析:
细节理解题。答案出自第二段:The particular stage of sleep in which the Belgian group is interested in is rapid eye movement(REM)sleep, when brain and body are active,heart rate and blood pressure increase, the eyes move back and forth behind the eyelids as if watching a movie, and brainwave traces resemble those of wakefulness.