Question

air pollution
clean air act
what do the united states and other countries use to reduce air pollution?
consumer choices
laws mandating lower emissions
promoting burning coal
voluntary actions by industries

Explanation:

The text mentions that air - pollution reduction in the US and other countries primarily relies on laws. Laws mandating lower emissions are a key tool for reducing air pollution as they set enforceable standards. Consumer choices and voluntary industry actions can contribute but are not the main approach. Promoting burning coal would increase air pollution, not reduce it.

Answer:

laws mandating lower emissions