What were the ancient Greeks' most important economic activities?

This is in my social studies book and I cant find the answer.

The Greeks had a diverse economy which mostly included trading within the city states of Greece itself - so the different city states (e. g. Sparta, Athens ...) traded between each other to supply each other with the resources the other did not have. Furthermore and more importantly, Greeks were a sea-faring nation and therefore traded by ships with others nations as well. Their maritime trading was something that was defining for them, as they had heavily relied on it.