Human activities like deforestation, pollution, global warming etc is a major threat to the natural resources.The scarcity of water is a common problem nowadays which needs serious attempts.Rainwater harvesting is the method of conservation of rainwater by reusing the stored water for several domestic purposes. The rainwater is collected from various hard surfaces such as rooftops and or other man-made above ground hard surfaces.
Sustainable water utilization is the vision of the management of natural resources like water and its proper utilization.
Encouragement of natural regeneration of vegetation is also one of the methods to conserve water resource. It will usually encourage species, that are already plentiful in the area and will ensure the vegetation is directly suited to the site. As all of the above are ways to conserve our water resources.
So, the correct answer is option D.