Which of the following correctly arranges the planets by the length of their year in increasing order? A)Venus < Earth < Mars < Saturn
B)Saturn < Mars < Earth < Venus
C)Mercury < Mars < Earth < Neptune
D) Neptune < Earth < Mars < Mercury

(please only answer if you know for sure)

answer:

sequence 1- deletion

                  2- duplication

                  3- insertion

                  4- substitute

                  5- inversion

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.