Photochemical smog can impact visibility and human health in large metropolitan areas. In order to reduce photochemical smog production and its impacts, which activity most directly reduces the causes of smog pollution?
A) Carpooling and reducing automobile use.
B) Reducing the reliance on nuclear energy.
C) Decreasing the use of landfills for municipal waste disposal.
D) Refusing permits to construct buildings taller than five stories.