The correct answer is: a) Census Act, 1948.
The Census Act, 1948 is an Act of the Parliament of India to provide for the taking of a census of the population of India at such intervals as may be specified by the Central Government. The Act also provides for the preparation of population tables and other statistical returns based on the census data.
The Registration of Births and Deaths Act, 1969 is an Act of the Parliament of India to provide for the registration of births and deaths in India. The Act also provides for the maintenance of registers of births and deaths and the preparation of statistical returns based on the registration data.
The National Population Register Act, 2003 is an Act of the Parliament of India to provide for the preparation of a National Population Register. The Act also provides for the maintenance of the National Population Register and the preparation of statistical returns based on the data in the National Population Register.
The Aadhaar Act, 2016 is an Act of the Parliament of India to provide for the establishment of a Unique Identification Authority of India and to provide for matters connected therewith or incidental thereto. The Act also provides for the issuance of Aadhaar numbers to individuals and the use of Aadhaar numbers for various purposes.
The Census Act, 1948 is the only Act among the given options that specifically provides for the taking of a census of the population of India. The other options provide for the registration of births and deaths, the preparation of a National Population Register, and the issuance of Aadhaar numbers, respectively.