People of Greenland are citizens of which of the following countries?

The correct choice is: Denmark

Greenland is a self-governing territory within the Kingdom of Denmark. It has had home rule since 1979 and self-government since 2009. Citizenship, foreign affairs and defence stay with Denmark. Greenlanders became Danish citizens with Danish passports when Greenland's colonial status ended in 1953. They are therefore Danish citizens, and through that also EU citizens, even though Greenland left the EU's predecessor in 1985.