The river valleys of the tigris-euphrates, the nile, and the indus were centers of civilization because they

c) troops march forward in close formation against newer, more accurate weapons

the answer is c sharecroppers were trapped in a cycle of poverty and debt.

explanation:

one of the major disadvantages of sharecropping system is that the sharecroppers or the planters are stucked in an unhealthy cycle of debts. this happens because planters will be allowed to loan merchandise from the land-owner and will soon be paid by the farmer in his share in the farm come harvest time. hope this !

by kd