Which action by humans could improve the
quality of the air?
(1) building homes that use only oil furnaces for
heat
(2) buying cars that get more miles per gallon of
gasoline
(3) increasing the number of coal-burning
power plants that generate electricity
(4) cutting down forests to clear land for factories

     The right answer to this question is: (2) buying cars that get more miles per gallon of  gasoline

Explanation:

     What happens is that, when we build homes that use only oil furnaces, this generates lots of pollution to the air, the same thing happen with coal-burning power plants, and the last one, cutting down trees to clear land is not only gonna generate more pollution with the construction of new factories, but it'll affect the animals that live there too. So buying cars that get more miles per liter will less the pollution of the air, but it will still be polluting, but it'll improve the quality of the air we breath.

the answer is 1. photosynthesis. glad to