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.