The correct answer is: a) Chennai and its suburbs.
The suburban railway network in Chennai is a commuter rail system that serves the city of Chennai and its suburbs. It is operated by the Chennai Suburban Railway, a division of the Southern Railway zone of the Indian Railways. The network consists of 128 stations and 168 route kilometers. The suburban railway network plays a crucial role in connecting Chennai and its suburbs. It is the most popular mode of transportation in Chennai, with over 4.5 million passengers using it daily. The suburban railway network is also a major source of employment in Chennai.
The other options are incorrect because:
- Option b) is incorrect because the suburban railway network does not connect major cities within Tamil Nadu.
- Option c) is incorrect because the suburban railway network does not connect tourist destinations.
- Option d) is incorrect because the suburban railway network does not connect industrial zones.