Which equation is correctly balanced?
A) CaO + 2H₂O + Ca(OH)₂
B) NH₃ + 2O₂ → HNO₃ + H₂O
C) Ca(OH)₂ + 2H₃PO₄ → Ca₃(PO₄)₂ + 3H₂O
D) Cu + H₂SO₄ → CuSO₄ + H₂O + SO₂