单项选择题
Do you wake up every day feeling too tired, or even upset If so, then a new alarm clock could bejust for you.
The clock, called Sleep Smart, measures your sleep cycle, and waits for you to be in your lightest phase of sleep (51) rousing you. Its makers say that should (52) you wake up feeling refreshed every morning.
A.claim
B.conclusion
C.concept
D.explanation