Transportation fuel sold in the United States must contain a minimum volume of what to reduce greenhouse gas emissions and the use of petroleum fuels?

• A. Ethanol
• B. Biodiesel
• C. Renewable energy
• D. Natural gas

Answer: (C)

The main idea is that a federal policy requires a minimum share of renewable fuels to be blended into transportation fuels sold in the United States, with the goal of cutting greenhouse gas emissions and reducing dependence on petroleum. Renewable fuels—like ethanol and biodiesel—are derived from renewable resources and typically produce lower lifecycle emissions than conventional petroleum fuels. The requirement is framed around the total volume of renewable fuels used, not just a single fuel, which is why the broad category renewable energy is the best fit. Natural gas isn’t considered a renewable fuel in this context, and while ethanol or biodiesel are examples of renewable fuels, the regulation targets the overall renewable-fuel blend.