Which is part of the theory of evolution by natural selection only the best adapted animal in the population survive evolution can only cause small changes to a species animals that survive cannot pass along the adaptation adaptation cannot be passed along to the next generation

prism b but im not for sure

digestion

it excretes wastes

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.