• Statement (I) is correct: In upland arid and semi-arid calcareous soils with high pH ($pH \gt 7.5$) and high free calcium carbonate ($CaCO_3$), iron precipitates into insoluble ferric hydroxides and carbonates ($Fe(OH)_3$), severely suppressing bioavailable divalent ferrous ($Fe^{2+}$) and triggering widespread lime-induced iron chlorosis in upland crops like groundnut and chickpea.
• Statement (II) is correct: Molybdenum (Mo) is a crucial metallic cofactor present in nitrogenase (within the FeMo-cofactor catalyzing biological atmospheric $N_2$ reduction) and nitrate reductase (catalyzing the reduction of nitrate $NO_3^-$ to nitrite $NO_2^-$), making it indispensable for leguminous symbiotic nitrogen fixation and microbial nitrate assimilation.
• Conclusion: Both Statement (I) and Statement (II) are correct. (Correct answer: Option 1)

• Standard Sequence of Field Protocols for Soil Salinity Assessment:
• Step 1 (D): Collection and laboratory analysis of representative soil samples to establish baseline saturation extract conductivity ($EC_e$).
• Step 2 (A): Calibration and field deployment of electromagnetic induction meters (e.g., EM38) or four-electrode Wenner array probes.
• Step 3 (C): Geospatial mapping and interpolation of bulk apparent electrical conductivity ($EC_a$) across the landscape.
• Step 4 (B): Delineation of spatial salinity management zones and formulation of leaching requirement plans.
• Conclusion: Correct chronological sequence is (D), (A), (C), (B), corresponding to Option 2.

Correct option: (2) (D), (A), (C), (B)