Step 1: GI tags protect products linked to a unique geographical origin and quality.
Step 2: Among the cashew belts listed, only Vengurla (Sindhudurg, Maharashtra) has an official GI registration for cashew nut quality.
Step 3: Kerala, Karnataka and Andhra Pradesh grow cashew but don't hold this specific GI tag.
Step 4: Correct answer: Vengurla, Maharashtra.