Explanation:

- Option 1: The challenge of organic farming

- Organic farming requires training, resources, and market access.

- It is more a change in practices than a lingering challenge.

- Option 2: Exploring options of sustainable livelihood

- Rural areas need diversified, sustainable income sources.

- This challenge involves creating new opportunities that can persist long-term.

- Option 3: Challenge of rural credit

- Access to credit is crucial for rural development.

- High-interest rates, lack of collateral, and limited financial institutions make it challenging for rural inhabitants to secure loans.

- Option 4: None of these

- This implies none of the listed options represent the primary challenge, which isn't the case.