Alternative 1:

"There was slavery. There was and is racism. There were racist songs. I know a lot of them because they're part of our musical -- and national -- history. I'm going to sing one for you. What do you think?"

alternative 2:

"There was slavery. There was and is racism. There were racist songs. I know a lot of them because they're part of our musical -- and national -- history. But I'm not going to sing any of them for you, because I think I already know what some of you may think."

Alternative 3:

"Oh, Susannah? No, sorry, I don't sing that. In fact, just about any song you can name might offend someone, so I don't sing them either. Just play the tune? Sorry, it might bring up a painful memory for someone and I daren't risk unknowingly causing pain. Why don't we all just sit quietly for a couple of hours and then go home and talk about what a great concert it was."