Question: What role does Ghanashyam Nayak play in India's longest running sitcom serial?
Sentence (from "Ghanashyam Nayak"): He is currently playing the role of Natwarlal Prabhashankar Undhaiwala a.k.a. Nattu Kaka in "Taarak Mehta Ka Ooltah Chashmah".
Relevant evidence: Yes