Step 1: Understanding the Concept:
The High Yielding Varieties Programme (HYVP) was a key initiative of the New Agricultural Strategy in India.
It marked the introduction of semi-dwarf, fertilizer-responsive varieties of major food grain crops to address severe food shortages.
Step 2: Detailed Explanation:
The HYVP was officially launched in the Kharif season of 1966.
The program focused on five primary crops: paddy, wheat, maize, jowar, and bajra.
The preparatory work and selection of the target areas took place in the preceding crop year, $1965 - 1966$.
Initially, the program targeted 100 districts across the country that possessed assured irrigation facilities and agricultural infrastructure.
This targeted approach ensured that inputs like high-yielding seeds, chemical fertilizers, and plant protection measures would yield maximum returns.
The success of this initial phase in these selected districts laid the foundation for the Green Revolution.
Step 3: Final Answer:
The High Yielding Varieties Programme was initially started with 100 districts in the country during $1965 - 1966$, which corresponds to Option (A).