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.

[Q]: Category: MUSIC 
Clue: Webster's defines this word as "a chord of three tones consisting of a root with its third and fifth"
[A]: a triad


[Q]: Category: HE WAS IN THAT? 
Clue: In 1969, in his pre-"Phantom" days, he played Cornelius Hackl in the film version of "Hello, Dolly!"
[A]: michael crawford


[Q]: Category: COLORFUL PHRASES 
Clue: In "Ivanhoe", when King Richard was in disguise he was described as this
[A]:
black knight