Question

romans built a system of sewers covered with stones. what was a result of this system? wastewater could be carried away from the city streets turned into rivers people stopped using buildings all farms were flooded

Explanation:

The Roman sewer system (covered with stones) was designed to manage wastewater. So the logical result is that wastewater could be carried away from the city. The other options (streets turning into rivers, people stopping using buildings, all farms flooding) don't relate to the purpose of a sewer system.

Answer:

Wastewater could be carried away from the city