Question

coal is a very dirty fossil fuel, but there are several advantages to using coal as a fuel source. for example, coal is energy dense and it is easy to transport. what is another advantage of coal production? it produces no air pollution. it is cheap.

Explanation:

Coal production and use: Coal burning releases pollutants like sulfur dioxide, so "It produces no air pollution" is wrong. Coal is relatively inexpensive compared to some other energy sources, making "It is cheap" a valid advantage.

Answer:

It is cheap.