Step 1: Examine the policy measures.
In the mid-1960s, India adopted several major policy measures to boost agricultural production:
Input subsidies: Subsidies on fertilizers, seeds, and irrigation.
Minimum support price (MSP): A guarantee to farmers for a minimum price for certain crops to ensure profitability.
Public storage: Establishment of food reserves to prevent shortages and price hikes.
Trade restrictions: Government-imposed restrictions to control agricultural exports and imports.
Step 2: Conclusion.
Thus, all of the above measures were implemented during the mid-1960s. Hence, the correct answer is (D).