The correct answer is: C. I and III.
The Alvars and Nayanars were Tamil Hindu saints who lived in the 6th to 9th centuries CE. They were devoted to the worship of Vishnu and Shiva, respectively, and their hymns are some of the most important texts in Tamil literature.
The Alvars and Nayanars were from all castes, and their hymns show that they were critical of the caste system. They often sang about the equality of all people in the eyes of God, and they condemned the discrimination that was practiced against people of lower castes.
The Alvars and Nayanars also played an important role in the development of bhakti, or devotional Hinduism. Their hymns helped to popularize the idea that God is accessible to all people, regardless of their caste or social status.
The importance of the traditions of the Alvars and Nayanars is sometimes indicated by the claim that their compositions were as important as the Vedas. This is a significant claim, as the Vedas are the most sacred texts in Hinduism. The fact that the Alvars and Nayanars were considered to be on a par with the Vedas shows the high regard in which they were held.
In conclusion, the Alvars and Nayanars were critical of the caste system and played an important role in the development of bhakti Hinduism. Their hymns are some of the most important texts in Tamil literature, and their traditions are still revered today.