Depends. Professionally I get accused of being a racist about 20% of the time I pull over a car driven by someone who isn’t white. The way I handle the charge is “I’m sorry you feel that way, but the reason I pulled you over was…”. That’s a technique trained in a verbal judo class and it works well enough.
In my personal life I’ve never been truly accused of racism, but if I was I’d use the second response of “Yeah? What are you going to do about it?”
That phrase, used in almost any situation, seems to get a rise out of anyone. I mean people really get pissed over it!
Wife: You didn’t take the garbage out!
Pk: Yeah? What are you going to do about it?
Wife: Uh, um?
The proper response, I guess, is “I’m going to dump it over your fucking head!”
But for some reason people get all flustered and storm off and don’t think of the snappy answer until an hour later.
I wouldn’t think of using that phrase in a professional setting.