According to the National Bureau of Soil Survey and Land Use Planning (NBSS&LUP), India is delineated into $20$ Agro-Ecological Regions (AERs) and $60$ Agro-Ecological Sub-Regions (AESRs) based on physiography, soils, bio-climate, and length of growing period (LGP). Option analysis: (A) $20$ & $60$ is the official NBSS&LUP classification. (B) $8$ & $15$ relates to Planning Commission broad agro-climatic zones ($15$). (C) $20$ & $40$ is incorrect. (D) $10$ & $25$ is incorrect.