Which of the Following Was NOT a Factor in the Decline

Which of the following was NOT a factor in the decline of the Greek city-states ?

A) Commerce naturally led to economic cooperation on which political unity among the city-states was built.
B) The city- states were prone to frequent wars.
C) Civic responsibility among citizens declined.
D) Free citizens were susceptible to demagogues.
E) Pride and overconfidence led to disaster.