Abrownish fossil that can be found in rock and contains the remain of an organism is
a) mold fossil
b) trace fossil
c) amber fossil
d) petrified fossil

so whats the answer

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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.