The Census collects data on the percentage of the population belonging to:

Scheduled Castes (SCs)
Scheduled Tribes (STs)
Other Backward Classes (OBCs)
All of the above

The correct answer is: D) All of the above.

The Census of India is a decennial census of India, conducted by the Office of the Registrar General and Census Commissioner, India. The first census was held in 1872, and the most recent census was held in 2011. The census collects data on a variety of topics, including population, age, sex, religion, language, education, and occupation.

The census also collects data on the percentage of the population belonging to Scheduled Castes (SCs), Scheduled Tribes (STs), and Other Backward Classes (OBCs). Scheduled Castes and Scheduled Tribes are groups of people who have been historically discriminated against in India. Other Backward Classes are groups of people who are considered to be socially and educationally backward.

The data collected by the census is used to plan and implement development programs, to allocate resources, and to monitor the progress of development. The data is also used to study social and economic trends, and to identify areas where there is a need for intervention.

The census is a vital tool for understanding the Indian population and for planning and implementing development programs. The data collected by the census is used to make decisions that affect the lives of millions of people.