A major fishing harbor in Tamil Nadu is:

Rameshwaram
Tuticorin
Chennai
All of the above

The correct answer is: d) All of the above.

Rameshwaram, Tuticorin, and Chennai are all major fishing harbors in Tamil Nadu.

Rameshwaram is a town and a municipality in Ramanathapuram district in the Indian state of Tamil Nadu. It is located on Pamban Island, which is separated from mainland India by the Pamban Strait. The town is known for its Hindu temples, including the Ramanathaswamy Temple, one of the most important pilgrimage sites in India. Rameshwaram is also a major fishing harbor.

Tuticorin is a city in the Indian state of Tamil Nadu. It is the headquarters of Tuticorin district and is located on the Gulf of Mannar. The city is known for its port, which is one of the largest in India. Tuticorin is also a major fishing harbor.

Chennai, formerly known as Madras, is the capital of the Indian state of Tamil Nadu. It is the fourth-largest city in India and the sixth-largest metropolitan area in India. Chennai is a major economic, cultural, and educational center in India. The city is also a major fishing harbor.