A third way to confirm this is by working from Vijay Singh's career milestones rather than his name or ancestry, since milestones are usually reported together with the golfer's home country.
- USA: When Singh reached World No. 1 in 2004, media coverage specifically highlighted that he was NOT American, making him notable as an overseas World No. 1, which rules this option out.
- Fiji: His major wins and world ranking are consistently reported as milestones for Fiji and the Pacific Islands, since he remains the most successful golfer of that background - this framing is what fixes his nationality as Fijian.
- India: Reports on his career distinguish his Indian-origin heritage from his actual nationality, always crediting his achievements to Fiji, not India.
- UK: His career achievements are never attributed to the UK in any golf record or ranking history.
This achievement-based framing points to the same country as before.
Hence, the correct answer is Fiji.