Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.

[Q]: Which 1970s musical film starred Angela Lansbury as a trainee witch?
[A]: angela lansbury


[Q]: The Byzantine Empire is the term used since the 19th century to describe the Roman Empire of the Middle Ages, centred on its capital, where?
[A]: byzantine empire


[Q]: After who is the Belfast City Airport named?
[A]:
george best belfast city airport