instruction:
Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
question:
Who is the only British Prime Minister to serve under 3 monarchs?
answer:
prime minister of the united kingdom


question:
The Bob Dylan songs 'Desolation Row', 'Tombstone Blues' and 'Like A Rolling Stone' featured on which album?
answer:
tombstone blues


question:
Who was the CBS News anchor-man known as 'the man Americans most trust'?
answer:

news presenter