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

[Q]: Which singer/songwriter, who began releasing hit singles in 1958, has had 3 albums (The Definitive Collection, Waking Up Is Hard to Do & The Music of My Life) on Billboard's Top 200 Albums chart between 2007 & 2010?
[A]: the definitive collection


[Q]: In which Shakespeare play do the characters Ajax, Achilles and Ulysses appear?
[A]: achilles


[Q]: Clyde Tonbaugh discovered what planet in 1930?
[A]:
clyde tombaugh