In order to address the challenges of varying intensities of floods and droughts in different parts of India, it is important to consider sustainable measures for agricultural production.

Option 1 suggests the provision of extensive irrigation facilities. This measure can be sustainable as it helps in managing water availability and ensuring crops receive adequate water during dry periods.

Option 2 suggests changing the crop calendar. This measure can also be sustainable as it involves strategically scheduling the planting and harvesting of crops to align with the availability of water and the absence of flood risks.

Option 3 suggests avoidance of flood and drought-prone areas for agriculture. This measure is not sustainable as it would involve completely abandoning these areas for agriculture. This would not only result in reduced agricultural production but also displace farmers who rely on these areas for their livelihoods. It is important to find ways to manage and mitigate the risks associated with floods and droughts rather than completely avoiding the affected areas.

Option 4 suggests an emphasis on selecting crops that are best suited to flood and drought conditions. This measure can be sustainable as it involves identifying and cultivating crops that are resilient and can adapt to challenging climatic conditions.

Therefore, among the given options, option 3 would not be a sustainable measure to address the impact of floods