An important port city and industrial center in Tamil Nadu is:

Erode
Vellore
Tuticorin
Thanjavur

The correct answer is c) Tuticorin.

Tuticorin is a port city in the Indian state of Tamil Nadu. It is located on the Gulf of Mannar, about 300 kilometers south of Chennai. Tuticorin is the second largest port in Tamil Nadu after Chennai. It is also an important industrial center, with industries such as oil refineries, fertilizer plants, and steel mills.

Erode is a city in the Indian state of Tamil Nadu. It is located in the Erode district, about 400 kilometers west of Chennai. Erode is a major commercial center and is known for its textile industry.

Vellore is a city in the Indian state of Tamil Nadu. It is located in the Vellore district, about 150 kilometers west of Chennai. Vellore is a major educational center and is home to the Vellore Institute of Technology.

Thanjavur is a city in the Indian state of Tamil Nadu. It is located in the Thanjavur district, about 300 kilometers south of Chennai. Thanjavur is a major cultural center and is home to the Brihadeeswarar Temple, a UNESCO World Heritage Site.