Which of the following are examples of modern biofuels?

• A. Ethanol and biodiesel
• B. Coal and natural gas
• C. Nuclear energy
• D. Hydroelectric power

Answer: (A)

Modern biofuels are fuels produced from recent biological materials like crops or organic waste, offering a renewable alternative to fossil fuels. Ethanol is produced by fermenting sugars or starches from plants such as corn or sugarcane, and is used to blend with gasoline. Biodiesel is made from fats or vegetable oils through a chemical process called transesterification and can power diesel engines. Because these fuels come from biomass that can be replenished, they’re renewable, and the CO2 released during combustion is largely offset by CO2 absorbed during plant growth, leading to potential lower net greenhouse gas emissions than fossil fuels when produced efficiently.

Coal and natural gas are fossil fuels formed from ancient organisms, not from contemporary biomass. Nuclear energy relies on splitting atomic nuclei, not bio-based fuels. Hydroelectric power uses the energy of moving water to generate electricity, not a fuel. Therefore, ethanol and biodiesel are the modern biofuels.