The correct answer is: Income source.
The Census of India is a decennial census of India. It is conducted by the Office of the Registrar General and Census Commissioner, India, under the Ministry of Home Affairs. The census is used to collect data on the population of India, including age, sex, religion, language, literacy, and occupation.
The census is not used to collect data on income source. This is because income is a sensitive topic and people may be reluctant to share this information. Additionally, income can be difficult to measure accurately.
The other options, age, sex, religion, and language, are all typically collected as part of the Census in Tamil Nadu.
Age is used to determine the age structure of the population. Sex is used to determine the sex ratio of the population. Religion is used to determine the religious composition of the population. Language is used to determine the linguistic composition of the population.