Q: This task is about creating an unanswerable question based on a given passage. Construct a question that looks relevant to the given context but is unanswerable. Following are a few suggestions about how to create unanswerable questions:
(i) create questions which require satisfying a constraint that is not mentioned in the passage
(ii) create questions which require information beyond what is provided in the passage in order to answer
(iii) replace an existing entity, number, date mentioned in the passage with other entity, number, date and use it in the question
(iv) create a question which is answerable from the passage and then replace one or two words by their antonyms or insert/remove negation words to make it unanswerable.
Passage: The FBI has maintained files on numerous people, including celebrities such as Elvis Presley, Frank Sinatra, John Denver, John Lennon, Jane Fonda, Groucho Marx, Charlie Chaplin, the band MC5, Lou Costello, Sonny Bono, Bob Dylan, Michael Jackson, and Mickey Mantle. The files were collected for various reasons. Some of the subjects were investigated for alleged ties to the Communist party (Charlie Chaplin and Groucho Marx), or in connection with antiwar activities during the Vietnam War (John Denver, John Lennon, and Jane Fonda). Numerous celebrity files concern threats or extortion attempts against them (Sonny Bono, John Denver, John Lennon, Elvis Presley, Michael Jackson, Mickey Mantle, Groucho Marx, and Frank Sinatra).
A:
Who has the FBI never maintained a file on?