Non-institutional sources of agricultural credit:
- NABARD: NABARD (National Bank for Agriculture and Rural Development) is a financial institution that provides credit facilities to farmers and rural development organizations. It offers various loan schemes and supports agricultural activities in rural areas.
- Commercial banks: Commercial banks play a significant role in providing agricultural credit. They offer loans to farmers for purchasing agricultural machinery, seeds, fertilizers, and other inputs required for farming. They also provide working capital loans for agricultural operations.
- Regional banks: Regional rural banks (RRBs) are specialized banks that focus on providing credit to the agricultural sector. They are governed by NABARD and offer loans to farmers at affordable interest rates.
- Traders: Traders in the agricultural sector often provide credit to farmers in the form of advances against future produce. This informal credit system allows farmers to meet their immediate financial needs by availing credit from traders against the promise of selling their crops to them.

Answer: D. Traders.
Traders are a non-institutional source of agricultural credit and provide advances to farmers against their future produce. This form of credit is widely prevalent in rural areas and helps farmers meet their immediate financial requirements. While NABARD, commercial banks, and regional banks are institutional sources of agricultural credit, traders play a significant role in the informal credit system.