Correct Option: C

Balaiyankutai in the pallava age was the name of a pound or tank. Majority of the irrigation tanks were built from the 6th to the 10th centuries of our era during the dynasty of the Pallavas. One will understand the importance of these systems of irrigation by noting that about one - third of the sureface area of the state is actually irrigated by these omnipresent tanks (about 40,000 such tanks), the two - thirds of water needs come from the exploitation of ground water.