They speak Danish. Danish is a North Germanic language http://www.omniglot.com/writing/danish.htm
People in Copenhagen, as well as the rest of Denmark, speak Danish. Danish is the official language of Denmark and is widely spoken throughout the country.
Danish, funnily enough. And the people are called "Danes".
God morgen
Ja, naturligvis.
Denmark, Greenland,
Don't think so.
In which countries the residents speak Danish? That would probably be Denmark. Danish is also a school-taught subject in Greenland from 1st grade.
Danes, Greenlanders and Faroese people (People from the Faeroe Islands). Only Danes speak it as their primary language. Norwegians speak a Norwegianised version of Danish when they speak 'Bokmål' which is the most commonly spoken version of the Norwegian language.
Most likely no, but who knows
He speaks Danish
you are mad but yes