• Plant Trace Element Concentrations:
• Manganese (Mn): Typical physiological requirement in plant tissue ranges around 0.1 to 0.5 ppm in solution culture $\rightarrow$ (I)
• Molybdenum (Mo): The lowest required micronutrient, functioning in nitrogen metabolism around 0.01 to 0.05 ppm $\rightarrow$ (III)
• Iron (Fe): Required in the highest relative concentration among micronutrients for chlorophyll synthesis and redox chains, typically 0.5 to 5.0 ppm $\rightarrow$ (IV)
• Zinc (Zn): Essential for auxin synthesis and enzyme activation, maintained around 0.02 to 0.2 ppm $\rightarrow$ (II)
• Systematic Match: (A)-(I), (B)-(III), (C)-(IV), (D)-(II) (Option 3).

Correct option: (3) (A) - (II), (B) - (Ill), (C) - (IV), (B) - (1)

• Copper $\rightarrow$ (III) Oxidases: Functional cofactor in copper-containing oxidases (ascorbic acid oxidase, tyrosinase, polyphenol oxidase) and the photosynthetic electron carrier plastocyanin.
• Nickel $\rightarrow$ (IV) Hydrogenases & Urease: Essential component of microbial hydrogenases and the plant urease enzyme that converts urea into ammonia.
• Molybdenum $\rightarrow$ (I) Nitrogenase & Nitrate Reductase: Moco cofactor drives nitrogenase, nitrate reductase, and xanthine dehydrogenase.
• Manganese $\rightarrow$ (II) Oxygen-Evolving Complex: Essential constituent of the water-splitting manganese cluster ($ ext{Mn}_4 ext{CaO}_5$) in Photosystem II.

Correct option: (1) (A) - (ill), (B) - (IV), (C)- 0, (B) - (I)