Many zamindaris in Tamil Nadu were located in regions like:

The correct answer is: d) Thanjavur delta.

A zamindari was a large landholding in British India, held by a zamindar, who was a hereditary landlord. The zamindars were responsible for collecting taxes from the peasants who lived on their land and paying them to the British government.

The Thanjavur delta is a region in the state of Tamil Nadu, India. It is located in the Cauvery River delta, and is one of the most fertile regions in India. The Thanjavur delta was a major center of zamindari rule during the British Raj.

The other options are incorrect because:

• Madurai and Tirunelveli are located in the Madurai and Tirunelveli districts of Tamil Nadu, respectively. These districts are not part of the Thanjavur delta.
• The Nilgiris is a mountain range in the state of Tamil Nadu. It is not part of the Thanjavur delta.
• The coastal districts of Tamil Nadu are located along the Bay of Bengal. They are not part of the Thanjavur delta.