Complete the sequence of fossil fuels: coal, ____, and natural gas.

Complete the sequence of fossil fuels: coal, ____, and natural gas.

• A. Water
• B. Coal
• C. Oil
• D. Gas

Answer: (C)

Fossil fuels are typically discussed as three main types: coal, oil, and natural gas. The sequence is completed by inserting oil, the liquid fossil fuel that sits between coal and natural gas in the standard grouping. Water isn’t a fossil fuel, so it doesn’t fit here. Repeating coal wouldn’t complete the progression, and using gas alone doesn’t align with the common three-part list since the third item is natural gas. So the missing term that fits the established order is oil.

Fossil fuels are typically discussed as three main types: coal, oil, and natural gas. The sequence is completed by inserting oil, the liquid fossil fuel that sits between coal and natural gas in the standard grouping. Water isn’t a fossil fuel, so it doesn’t fit here. Repeating coal wouldn’t complete the progression, and using gas alone doesn’t align with the common three-part list since the third item is natural gas. So the missing term that fits the established order is oil.