Tankas are _____.

The correct answer is Option (1) → Rounded holes which are usually cemented or tiled to collect drinking water

Tankas are a traditional way of rooftop rainwater harvesting in the dry parts of Rajasthan, such as Bikaner, Phalodi and Barmer. A tanka is an underground tank or pit, usually round, lined with cement or tiles, built in the courtyard or under the house.

Rain falling on the sloping roof is carried down a pipe into the tanka and stored there. The water is used for drinking, especially in the summer months when no other source is left, and the tank also keeps the room above it cool.