Wtf..

[A_Forever]

"I went to bed at 8 'clock in the evening and wound up my clock and set the alarm to sound at 9 'clock in the morning. How many hours sleep would I get before being awoken by the alarm?"

13? Right? I'm a bit confused since my only choices for an answer were:

A. How should I know?

B. Hmm..

C. 1 hour.

D. 18hrs.

I'm going to feel really dumb if someone one here points something out that I missed and makes me realize its a trick question T_________T I just don't get it. (Edit: I think I might get it now... But I still want someone to give me the answer AND explain it xD)