Q.__________ is known as "Gateway of Tamil Nadu".

The headquarters of Southern Railway is at Chennai, so the answer is option (d).

Southern Railway is one of the oldest zones of the Indian Railways and forms a key part of Tamil Nadu's transport infrastructure, connecting the state with Kerala, Karnataka, Andhra Pradesh and Puducherry. Its zonal headquarters is located at Chennai (Park Town). Efficient rail connec …

Thoothukudi is known as the "Gateway of Tamil Nadu" because of its major port.

A "gateway" city is one through which a region's external trade passes. Thoothukudi (Tuticorin) has one of India's major sea ports and handles a large share of Tamil Nadu's export–import trade, making it the state's principal maritime entry and exit point. This role as a trade gateway and port-based growth centre is why it is called the "G …

The third largest international airport in India is Chennai.

In the Tamil Nadu HSC Commerce syllabus, the Tamil Nadu Economy unit highlights Chennai as the state's principal urban growth centre with well-developed transport infrastructure. The Chennai International Airport (Meenambakkam) handles a very large volume of domestic and international passenger and cargo traffic. Among India's airports it ranks after Delhi and Mumbai, making it the third largest internation …