TASK DEFINITION: You are given a concept, and a list of answers. You should generate a question about the concept that leads to the given answer(s).
PROBLEM: concept: Zac Efron  answers:  ['17 Again', 'Charlie St. Cloud', 'Miracle Run', 'Me and Orson Welles', "Melinda's World", 'High School Musical', 'The Derby Stallion', 'High School Musical 2', 'High School Musical 3: Senior Year', 'Hairspray']

SOLUTION: what movies does zac efron star in?

PROBLEM: concept: Riannah  answers:  ['This Is the End', 'Battleship', 'Happy Smekday!']

SOLUTION: what movie did rihanna play in?

PROBLEM: concept: Darth Vader  answers:  ['Matt Lanter']

SOLUTION:
who voices anakin in the clone wars?