Which type of fuel is considered non-renewable?

The correct choice is fossil fuel because it is derived from the remains of ancient plants and animals and is found deep beneath the Earth’s surface. Fossil fuels—such as coal, oil, and natural gas—take millions of years to form and cannot be replenished on a human timescale. Once extracted and used, they are gone for good, leading to their classification as non-renewable resources.

In contrast, the other options—wood pellets, biofuel, and pine oil—are all classified as renewable. Wood pellets are made from organic materials, which can be replenished through sustainable forestry practices. Biofuel is derived from recent biological material, such as crops or animal waste, which can be continuously produced. Pine oil is extracted from pine trees, which can grow back, making it renewable as well. Therefore, fossil fuel stands out as the only non-renewable option in this context.