The correct answer is: a) Office of the Registrar General & Census Commissioner.
The Office of the Registrar General & Census Commissioner is the agency responsible for conducting the Census in India. It is a statutory body under the Ministry of Home Affairs. The Census is conducted every 10 years and provides a comprehensive snapshot of the population of India. It is used to plan for development and to monitor progress towards national goals.
The National Statistical Commission is an independent body that advises the government on statistical matters. It does not conduct the Census.
The Planning Commission was a government body that was responsible for planning economic development in India. It was abolished in 2014 and its functions were transferred to the National Institution for Transforming India (NITI Aayog).
The Ministry of Home Affairs is a government ministry that is responsible for internal security, law and order, and border management. It does not conduct the Census.