Why Is It That People in Online Computer Gaming Forums

Why is it that people in online computer gaming forums or Internet chatrooms may be more likely to speak in aggressive or derogatory manners to other users,compared to the interaction styles they might use when communicating face-to-face?

A) because everyone else in the room usually does that and they are yielding to the effects of normative conformity
B) because they usually know how to sever their connection before they can be identified by the person that they are insulting
C) because they know that people playing the same games or frequenting the same forums will understand that they are just kidding
D) because they experience the deindividuation that is afforded by anonymity