Option (D) is correct
The eco-friendly activity is using windmills to generate power for irrigation.

Solar energy, wind energy, and geothermal energy are some environmentally friendly forms of energy as they do not pollute the environment. They are also unlimited, hence their use is renewable. Wind energy is used in windmills for the generation of electricity and irrigating fields. Option (A) is incorrect
The eco-friendly activity is using windmills to generate power for irrigation; not using cars for transportation as using vehicles produces harmful gases from the combustion of fuels that pollutes the environment. Option (B) is incorrect
The eco-friendly activity is using windmills to generate power for irrigation; not using polybags for shopping. As polybags are non-biodegradable, they remain in the environment for very long and cannot be recycled. Option (C) is incorrect
The eco-friendly activity is using windmills to generate power for irrigation; not using dyes for coloring clothes. As these colored dyes enter the rivers through the household wastewater and industrial sewage, they pollute the water drastically.