Given an trivia question precisely answer the question with a word/phrase/name. External resources such as Wikipedia could be used to obtain the facts.

Three of the Galilean moons of Jupiter are Io, Europa and Callisto. Which is the fourth?
ganymede

What is the name ofthe seventh and final 'Harry Potter' book due out in July 2007?
harry potter and the deathly hallows

Which Pakistani cricketer married the English socialite Jemima Goldsmith in 1995?

imran khan