The question asks to identify the country that was the primary source of Foreign Direct Investment (FDI) into India for the financial year 2024-25.
Based on the provided information, the key countries considered as sources for FDI in India for FY 2024-25 include:
Mauritius has historically been a significant contributor to India's FDI inflows, often due to favorable tax treaties like the Double Taxation Avoidance Agreement (DTAA). While other nations like Singapore and the USA also invest heavily, official reports and preliminary data for FY 2024-25 indicate that Mauritius remains the top source country for FDI in India.
Therefore, the correct option identifies Mauritius as the leading source of FDI.