What is one way to reduce outdoor air pollution from coal-burning facilities? 

A)  cap-and-trade 
B)  convert coal to gaseous fuel 
C)  partial zero emissions 
D)  emissions cap

The best way to reduce outdoor air pollution from coal-burning facilities is to convert coal to gaseous fuel. Coal gasification is a process of converting coal into a gaseous fuel that can be burned cleanly. This process removes impurities from the coal, which reduces emissions of sulfur dioxide, nitrogen oxides, and particulate matter. The resultant gas is also easier to transport and use in power plants or industrial processes, making it a more efficient and environmentally friendly solution compared to traditional coal burning methods.