In which sentence are the commas used correctly?
A)	On Friday before the big game, I had trouble concentrating on my school work.	
B)	On Friday, before the big game, I had trouble concentrating on my school work.	
C)	On Friday before, the big game, I had trouble concentrating on my school work.	
D)	On Friday before the big game, I had trouble, concentrating on my school work.