The correct option is D All the above
Rainwater harvesting is the accumulation and storage of rainwater for reuse rather than allowing it to run off. Dams are the large structures that are constructed to ensure the adequate storage of water not just for irrigation, but also for generating electricity. Canals are human-made channels for water conveyance majorly for irrigation purposes. Rain water collected from the rooftops and stored in tanks also comes under water harvesting.