• Carbonic anhydrase $\rightarrow$ (II) $\text{Zn}^{2+}$: Contains an essential zinc ion coordinated by three histidine residues that activates water for hydration of $\text{CO}_2$ to $\text{HCO}_3^-$.
• Hexokinase $\rightarrow$ (IV) $\text{Mg}^{2+}$: Requires magnesium ($ ext{Mg}^{2+}$) as a cofactor to chelate the negative charges of ATP, forming the true active substrate $\text{MgATP}^{2-}$.
• Nitrate Reductase $\rightarrow$ (I) Mo: Contains a molybdenum pterin cofactor (Moco) essential for transferring electrons to reduce nitrate ($\text{NO}_3^-$) to nitrite ($\text{NO}_2^-$).
• Urease $\rightarrow$ (III) $\text{Ni}^{2+}$: A nickel-dependent metalloenzyme that hydrolyzes urea into ammonia and carbon dioxide.

Correct option: (4) (A) - (II), (B) - (IV), (C) - (1), (DB) - (Ill)