Step 1: Distinguish Alvar vs Nayanar: A simple rule: Alvars = Vishnu bhaktas; Nayanars = Shiva bhaktas. This distinction is the single most tested fact about the Tamil Bhakti movement.
Step 2: Apply it here: Since the question asks specifically about Nayanars, the answer must be the Shiva-devotee group, not Vaishnavite.
Final Answer: (A) Follower of Shaiv religion. Note: the source paper's own marked answer circles (C) Vaishnavite, which is factually incorrect — Nayanars are the Shaivite saints; Alvars are the Vaishnavite ones.