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

[Q]: Established in 1919, which is the world's oldest surviving airline?
[A]: airline


[Q]: Which country is currently ruled by the Chakri dynasty that has been in power since 1782?
[A]: chakri dynasty


[Q]: Which London landmark was designed by Sir Christopher Wren to commemorate the Great Fire of London?
[A]:
christopher wren