The correct answer is A) Goa and Maharashtra.
The Mahadayi river originates in Karnataka and flows through Goa and Maharashtra before joining the Arabian Sea. The dispute between Karnataka and Goa over the sharing of the Mahadayi river water has been going on for over two decades. Karnataka has been demanding that Goa release more water from the Mahadayi river for drinking and irrigation purposes, while Goa has been resisting this demand, citing environmental concerns. The dispute has been referred to the Supreme Court of India, which is currently hearing the case.
The other options are incorrect. Option B is incorrect because Kerala and Tamil Nadu are not involved in the Mahadayi Water Dispute. Option C is incorrect because Andhra Pradesh and Telangana are not involved in the Mahadayi Water Dispute. Option D is incorrect because Madhya Pradesh and Chhattisgarh are not involved in the Mahadayi Water Dispute.