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-state?

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.