Question

Which situation is the best example of dramatic irony? A. A young man fights aliens and becomes a hero; at the end of the story, the reader learns that it was all a dream. B. A police detective uses clues to track down a murderer, only to discover that his partner is committing the crimes. 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. D. A college student stays up all night studying for a test, only to find out the next day that the test is canceled.

Answer 1

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.