The Ropar Thermal Power Plant is primarily connected to the grid through:

Transmission lines
Inland waterways
Rail network
None of the above

The correct answer is: a) Transmission lines.

Transmission lines are the high-voltage power lines that carry electricity from power plants to substations. The Ropar Thermal Power Plant is a coal-fired power plant located in Ropar, Punjab, India. It has an installed capacity of 1,320 MW. The plant is connected to the grid through a 400 kV transmission line.

Inland waterways are a network of rivers, canals, and other waterways that are used for transportation. Rail networks are a network of railways that are used for transportation. None of these options are correct because the Ropar Thermal Power Plant is connected to the grid through transmission lines.