TASK DEFINITION: You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For simplicity, answers should be in all lower cased letters.
PROBLEM: Category: HE WAS IN THAT? 
Clue: In 1969, in his pre-"Phantom" days, he played Cornelius Hackl in the film version of "Hello, Dolly!"

SOLUTION: michael crawford

PROBLEM: Category: CANADIAN BAL-EH? 
Clue: Alberta Ballet's "The Fiddle and the Drum" is set to the songs of this female singer born in Alberta

SOLUTION: joni mitchell

PROBLEM: Category: PSYCHOLOGY 
Clue: Extroverts & introverts are opposing types in this Swiss psychiatrist's theory

SOLUTION:
carl jung