The country-wide Economic Census is undertaken by the National Sample Survey Organization (option 2). The Department of Expenditure (option 1) is responsible for formulating and implementing budgetary policies and controlling government expenditure. The Planning Commission (option 3) was responsible for formulating five-year plans for the socioeconomic development of the country, but it has been replaced by the NITI Aayog, so it does not undertake the economic census. The Central Statistical Organization (option 4) is responsible for coordinating statistical activities in India and conducting surveys to gather data on various aspects of the economy. However, the economic census is conducted by the National Sample Survey Organization. Therefore, the correct answer is option 2.