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.

Category: CANADIAN CITIES 
Clue: The name of this provincial capital means "queen" in Latin
regina, saskatchewan

Category: MUSICAL THEATER 
Clue: In France, this musical was known as "Brillantine"; in Mexico, it was "Vaselina"
grease

Category: 20th CENTURY INNOVATIONS 
Clue: After watching smoke emitted by WWI airplanes, Major J.C. Savage developed the technique for this

skywriting