I would go for C. I don't think that shaming the student is a good idea, and also I am so ridiculously non-combative that I wouldn't be able to do so anyway. I might quietly ask them to see me after class as they were leaving, so I could go for a form of D. And I would be really really hoping for E to happen, but then I'd have to try and make it into a nice negotiated discussion, so part of me would also be hoping the rest of the students would just be wtfacing at the other student.