Which of the following sources generates the largest percentage of U.S. electricity?

The correct answer is coal-generated electricity. Historically, coal has been one of the primary sources of electricity generation in the U.S. for many years, particularly before the rise of natural gas and renewable energy sources. Although there has been a significant shift towards natural gas and renewable energy in recent years due to environmental regulations and market dynamics, coal still contributed a substantial portion of the energy mix for electricity generation at various points.

It's important to consider that while natural gas has become a leading source due to its lower emissions and economic viability, coal has historically dominated electricity production for a long time. Nuclear power, on the other hand, provides a smaller share compared to coal and natural gas, while renewable sources, though growing rapidly, still account for a smaller percentage relative to traditional fossil fuels like coal and natural gas.

Therefore, the significance of coal in the context of U.S. electricity generation remains a key part of understanding the energy landscape and its evolution over time.