The correct answer is D. a heavy shower of rain.
Rainwater is the purest form of water because it is naturally filtered through the atmosphere and the Earth’s surface. As rain falls, it picks up dust and other particles from the air. These particles are then washed away by the rain as it flows over the ground. The rain also dissolves minerals from the Earth’s surface, but these minerals are usually present in very small amounts. As a result, rainwater is very clean and safe to drink.
Deep tubewells, running streams, and hot water springs can all contain impurities. Deep tubewells may contain bacteria or other contaminants from the surrounding soil. Running streams may be contaminated with runoff from farms or factories. Hot water springs may contain minerals that can be harmful to health.
Therefore, the purest form of water can be obtained from a heavy shower of rain.