More detainees bid good-bye to the jail in Guantanamo Bay, Cuba, while Iran freed four Americans as part of a prisoner swap. And scientists discovered a ninth planet in our solar system (sorry, Pluto). Take our 5-minute quiz about all of these events.
World news quiz: Prisons just got lighter in Guantanamo and Iran
World
Jan 22, 2016 9:10 AM EDT