Which answer best defines the civic virtue “common good”?

(05.04 mc) how did the roman transportation system keep the empire strong? plz

Why was the united states motivated to establish the open door policy? a. the policy guaranteed american commerce with china. b. the policy supported the chinese nationalist cause. c. the policy led to a gain of american colonies in asia. d. the policy claimed damages from the chinese.

Were the terms of the treaty of versailles reasonable?