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: MUSIC 
Clue: Webster's defines this word as "a chord of three tones consisting of a root with its third and fifth"

SOLUTION: a triad

PROBLEM: Category: OFFICIAL LANGUAGES 
Clue: Official language in common to the Central African Republic & Canada

SOLUTION: french

PROBLEM: Category: BUILDING BRIDGES 
Clue: In Thailand a sound & light show depicts the bombing of this bridge built by P.O.W.s

SOLUTION:
the bridge on the river kwai