Explanation:

- Multiple cropping: Planting more than one crop in the same field throughout the year. It helps in improving food security but does not directly protect against natural disasters.

- Green revolution: An agricultural transformation that increased crop production through modern inputs. It emphasizes yield but doesn't directly safeguard against natural calamities.

- Crop insurance: ?? The correct answer. It provides financial protection to farmers against losses due to natural calamities, ensuring a safety net for their investments.

- HYV (High Yielding Variety): Seeds developed for higher production; while beneficial for crops, they don't directly protect against disasters.