Which one of the following south Indian states has the highest groundwater utilisation (in per cent) of its total ground water potential?

Tamil Nadu

The correct answer is Option 1: Tamil Nadu

Tamil Nadu has the highest groundwater utilisation among the given South Indian states while the lowest is in Kerala.

NCERT: "The total replenishable groundwater resources in the country are about 432 cubic km. The level of groundwater utilisation is relatively high in the river basins lying in north-western region and parts of south India. The groundwater utilisation is very high in the states of Punjab, Haryana, Rajasthan, and Tamil Nadu. However, there are States like Chhattisgarh, Odisha, Kerala, etc., which utilise only a small proportion of their groundwater potentials. States like Gujarat, Uttar Pradesh, Bihar, Tripura and Maharashtra are utilising their groundwater resources at a moderate rate."