Science question, oh- a base or neutral?

A few days ago I had a physical science test. one of the questions was, if OH- is alone, is it an base or neutral. I picked base. but can anyone explain to me why it was a base and not neutral?
please answer asap
Jess

it's a base because it can accept protons... (because it is negatively charged, it can accept a positive proton...)
http://en.wikipedia....

neutral means it doesnt lose or gain any protons (it's not positively or negatively charged)

thank you !!