Which Pixar film revolves around a rat who dreams of becoming a chef?

Ratatouille

Who wrote the young adult dystopian novel 'Divergent'? What pop singer is nicknamed the "Princess of Pop" and released the album "...Baby One More Time"? What mystical city provides Doctor Strange training in the mystical arts? What is the capital city of South Africa? Who are the main villains in the Halo series fought primarily by Master Chief?