Oklahoma is the nation’s leading producer of

Oklahoma is the nation's leading producer of fossil fuels, primarily natural gas and oil.

Explanation:

Oklahoma is an important natural gas producer (second largest US natural gas producer). Although oil production and refining have historically dominated the state’s economy, the collapse in the energy industry during the 1980s resulted in the loss of nearly 90,000 energy-related jobs between 1980 and 2000 and seriously damaged the local economy. Despite that, Oklahoma is the third largest oil producer in America.

determination