The correct option is A Tolk¯appiyam
Tolkappiyam is the earliest extant work of Tamil Literature and linguists. Tolkappiyam derived from the combination of two words 'Tonmai (ancientness) and 'kappiyam' (literature). It comprises three books- the Ezhuttadikaram, the Solladikaram, and the Poruladikaram. It grammatises the use of words and syntaxes and moves into the higher mode of language analysis.