Option b is the correct answer. In Sangam Literature, 'Tolkappiyam' is a text of Tamil grammar. It is one of the oldest Tamil work and some in the Tamil tradition place the text in the mythical second sangam, variously in 1st millennium BCE or earlier. It was written by Tolkappiyar, who is believed to have been a disciple of the sage Agastya. The text covers various aspects of the Tamil language, such as phonology, morphology, semantics, syntax, and prosody. It also provides information about the social and cultural life of the ancient Tamils, such as their customs, ethics, polity, and geography.