The correct answer is Nagapattinam.
Nagapattinam is a district in the Indian state of Tamil Nadu. It is located on the Bay of Bengal and has a coastline of 240 kilometers. The district is known for its temples, beaches, and fishing villages.
Kanyakumari is a district in the Indian state of Tamil Nadu. It is located at the southernmost tip of India and has a coastline of 72 kilometers. The district is known for its beaches, temples, and churches.
Chennai is the capital of the Indian state of Tamil Nadu. It is located on the Coromandel Coast and has a coastline of 118 kilometers. The city is known for its beaches, temples, and museums.
Thanjavur is a district in the Indian state of Tamil Nadu. It is located on the Cauvery River and has a coastline of 100 kilometers. The district is known for its temples, palaces, and historical monuments.
Nagapattinam has the longest coastline in Tamil Nadu because it is located on the Bay of Bengal, which is a large body of water. The other districts are located on smaller bodies of water, such as the Coromandel Coast and the Cauvery River.