Which one of these things did Dumbledore leave to Ron?

Which one of these things did Dumbledore leave to Ron?
A. a book about the greatest Quidditch tournaments in wizard history
B. a key, which would open any locked door inside of Hogwarts
C. the Extendable Ears that were taken away from Ron his first year
D. a Deluminator, which could suck all light from a place and restore it