QOD: have you downloaded Ecosia yet? why not? do it. n o w.

they had the law tat factories that produces smoke cannot be built near residential buildings.

building of proper sewage system was done to ensure that the waste is carried away from the humans so that they do not get diseases from it.

also they built water systems to provide water in those areas which are drought prone.

if you listed your answers right then i believe your answer is b.

i think this picture will you.