GKFix MCQ Question

In which of the following reactions does ammonia act as a ligand?

• A. NH₃ + H⁺ → NH₄⁺
• B. N₂ + 3H₂ → 2NH₃
• C. Cu²⁺(aq) + 4NH₃(aq) ⇌ [Cu(NH₃)₄]²⁺(aq)
• D. 2NH₃ + 3CuO → N₂ + 3Cu + 3H₂O