The correct answer is option 'C' - Purusa-sukta of Rig Veda.

The Purusa-sukta is a hymn found in the 10th mandala (book) of the Rig Veda, one of the oldest sacred texts of Hinduism. It describes the creation of the universe and the origin of the four varnas (castes) in ancient Indian society. The hymn is composed in the form of a dialogue between different parts of the cosmic being, known as Purusha.

The fourfold division of society, known as the varna system, is mentioned in the Purusa-sukta. According to this hymn, the cosmic being Purusha is described as having four parts, which are associated with the four varnas. These varnas are:

1. Brahmins (priests and scholars): The hymn describes the mouth of Purusha as representing the Brahmins, who were considered to be the highest varna. They were responsible for studying and teaching the Vedas, performing rituals, and guiding society spiritually.

2. Kshatriyas (warriors and rulers): The hymn states that the arms of Purusha symbolize the Kshatriyas, who were responsible for protecting society, ruling over kingdoms, and maintaining law and order.

3. Vaishyas (merchants and farmers): The hymn mentions that the thighs of Purusha represent the Vaishyas, who were engaged in agricultural activities, trade, and commerce. They were responsible for producing and distributing goods in society.

4. Shudras (laborers and servants): The hymn describes the feet of Purusha as symbolizing the Shudras, who were considered to be the lowest varna. They were responsible for performing manual labor, serving the higher varnas, and assisting in various tasks.

The varna system was a hierarchical social structure that determined a person's occupation, status, and role in society based on their birth. It was believed to have originated from the cosmic order and was considered to be divinely ordained. Each varna had its own rights, duties, and responsibilities, and intermarriage between varnas was generally prohibited.

The Purusa-sukta is an important text in understanding the origins and development of the caste system in ancient India. It reflects the social structure and values of the Vedic age and provides insights into the religious, cultural, and social aspects of that time.