instruction:
Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
question:
Who was Minister-Chairman of the Russian Provisional Government and Prime Minister of Russia from 21 July 1917 (following the abdication of Tsar Nicholas II) to 8 November 1917 (the Bolshevik revolution), who is buried in Putney Vale Cemetery, London?
answer:
russian revolution


question:
Which film was based on the story The Sentinel by Arthur C Clarke?
answer:
arthur c. clarke


question:
Who, as the first chairman of the British Rail Board, infamously directed the huge reduction in railway lines across the UK in the 1960s?
answer:

british railways board