Read the following passage carefully and then choose the best option to fit each space.
Air, water and soil ___(1)___ necessary to the survival of all living things. Badly polluted air can ___(2)___ illness, and even death. Polluted water kills fish and ___(3)___ marine life. Pollution of the soil reduces the amount ___(4)___ and that is available for growing food. The pollution problem is very complicated ___(5)___ much pollution is caused by things that benefit people.