9. Which of the following is the independent variable in the experiment? a. Soil
b. Amount of water
C. Temperature
d. Color of light

b

Explanation:

if you add everything up correctly you should get 69 i got this because 50 plus 19 is it

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.