I started puttering around ( ), not knowing what I was doing.

I started puttering around ( ), not knowing what I was doing.
A、within
B、besides
C、outside
D、except
【正确答案】：C
【题目解析】：本题考查介词辨析。within“在….内部”， besides“除了”， outside“在…以外”， except“除了”。句意：我开始在外面闲荡，不知道自己在做什么。故选C。