Concept:Environmentally friendly energy sources are those that produce little or no pollution and come from renewable or sustainable resources.
Explanation:Energy sources are considered environmentally friendly if they do not release harmful emissions or deplete natural resources.
Wind energy is clean, renewable, and produces no air pollution.
Biogas is produced from organic waste and burns more cleanly than fossil fuels.
Coal and thermal energy are usually derived from fossil fuels, which release carbon dioxide and other pollutants.
Therefore, the pair that is truly environmentally friendly is wind and biogas.
The correct choice is Option B.
Answer:B. Wind and biogas