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 consistency, answers should be in all lower cased letters.

Category: MOVIE REVIEWS 
Clue: (Hi, I'm Garry Marshall.) I directed this 1990 movie that the New York Times said "Borrows a thing or two from Pygmalion....but has its own....wit"
pretty woman

Category: CAN'T SMILE WITHOUT YOU 
Clue: It's the hard outer layer of a tooth
enamel

Category: PREFIXES 
Clue: This prefix turns 1 byte of data into about a billion

giga-