02 Grand Prix wiring for rear speakers

My brother blew one of his rear speakers in his 2002 Grand Prix SE, and when we went to replace them, the wires aren't marked as far as which one is positive and which one is negative. Instead they were marked A & B, with there being a light and dark blue wire on the passenger's side, and a dark brown and light yellow wire on the driver's side of the car. Any ideas as to which wire is positive and which is negative?

Wiring to Rear Speakers. Size: 6x9".

RR(+) : DK.BLU
RR(-) : LT.BLU
LR(+) : BRN
LR(-) : YEL