Which of the following is classified as a non-renewable resource?

Natural gas is a fossil fuel that is formed from the remains of ancient marine organisms buried under layers of sediment and rock for millions of years. It is classified as a non-renewable resource because it exists in finite quantities and cannot be replenished on a human timescale once it is depleted. The extraction and consumption of natural gas contribute to environmental issues, including greenhouse gas emissions.

In contrast, solar energy, wind energy, and hydropower are all renewable resources. These sources are continually replenished by natural processes—solar energy is harnessed from sunlight, wind energy is derived from atmospheric movements, and hydropower utilizes the flow of water. As long as these natural processes continue, the energy they produce can be harnessed without depleting the resource itself.