The classical civilizations of india and china shared which of the following traits with the roman empire?

a. they all had agricultural economies
b. they were all ruled by the warrior class
c. they all relied on slavery for production
d. they all followed the same religion

The correct answer in this case is that A - They all had agricultural economies.

The reason why this is so is because having a big civilization brings a demand for a lot of food with it. This is something all of the civilizations shared between each other. All of them were big and required a lot of food to be able to sustain themselves - and supplying a civilization with big amounts of food was most easily done by agriculture.