C. A talk-show audience is aware that a man's first love is hidden backstage as he confesses his wish to see her again.
Dramatic irony - think Drama class, on stage. Dramatic irony is when the audience knows something but not everyone involved does. In this case the audience knows about the girl backstage, but the man does not.
Other types of irony: verbal irony - sarcasm, when someone says one thing, but means something else. Situational irony is when something unexpected happens.