At present which is the biggest thermal power plant in India?
A) Talcher
B) Mundra
C) Vindhyachal power station
D) Digboi

Hint:
The Vindhyachal power station was started in 1982 and has the capacity of 4760 megawatt. It currently has thirteen units working. It is managed by National Thermal Power Corporation Limited, NTAC.

Complete step by step solution:
The Vindhyachal power station is situated in Singrauli district of Madhya Pradesh. There were stages of development of this power station. They are as follows,
The stage one of development involves the commissioning of six units of two hundred and ten megawatt between the year 1987 and 1991.
The stage two of development comprises commissioning of two coal fired units of five hundred megawatt between the year 1999 and 2000.
The stage three of development includes commissioning of another two coal fired units of five hundred megawatt between the year 2006 and 2007.
Stage four is similar to stage three. It includes commissioning of two more core fired units of five hundred megawatt between the year 2012 and 2013.
The stage five of development involves commissioning of a single unit of five hundred megawatt. It was done in the year 2015.
The boilers and turbines of all seven units of five hundred megawatt were supplied by Bharat Heavy Electricals.
Coal supply: The coal for Vindhyachal thermal power plant is supplied by Nighai and Dudhichua coal mines of the northern coalfields.

Hence Vindhyachal is the biggest thermal power plant of India. Therefore, the correct option is C.

Additional information:
In many power plants, water is heated to convert it into steam. The steam is used to rotate the turbines. In this way, the heat energy is converted into mechanical energy and then this mechanical energy is converted into electrical energy. So, the intermediate is mechanical energy.

Note:
A thermal power station is a power station in which heat energy is converted into electrical energy. The source of heat used is mostly coal.