Final answer:
Option (a). Building a geothermal power plant is the option that uses renewable energy, as geothermal energy is sustainable and emits no greenhouse gases, making it a clean and steady power source.
Step-by-step explanation:
Among the options provided, building a geothermal power plant utilizes renewable energy. Geothermal energy harnesses heat from the Earth's core, which is a continuous and sustainable energy source. This energy is often accessed by drilling wells to reach underground reservoirs of steam and hot water, which can then turn turbines to generate electricity.
Unlike burning fossil fuels like coal and oil, geothermal energy does not result in greenhouse gas emissions and is considered a cleaner, sustainable option. Furthermore, it does not suffer from the intermittency issues that other renewables like solar and wind may experience, making it a steady power source.
It is important to note that while geothermal energy is available at tectonic plate boundaries and can provide significant benefits, it might not be economically feasible or scalable to be a major part of the overall energy mix everywhere. Nevertheless, it stands as the only option listed that is renewable and has the potential for a significantly lower environmental impact compared to the non-renewable alternatives provided.