Correct Option: D

Solar, wind and hydro power are examples of cleanest energy sources. According to a new US study, Greenhouse gases produced over the lifetime of a wind turbine are less than that of fossil-fuel based energy sources and most other renewables. Only ocean energy (wave and tidal) and hydropower have lower emissions than wind. As a clean, fuel-free source of energy, wind turbines create energy without generating the damaging pollutants.