Context: Humans have invented many ways to use energy from natural resources. Some of these uses of energy add to air pollution, and others do not.
Hint: Burning a material such as wood, oil, or coal releases chemicals that add to air pollution.
Below are three examples of using energy from natural resources. Select the use of energy that did not add to air pollution.
A. The engine on a garbage truck burned natural gas.
B. Many early railway locomotives had engines that burned coal.
C. Wind turned the blades of a windmill that was used to grind wheat into flour.
Pick the correct answer from the listed options and provide the letter of the selected option.
Answer: C