Balance the chemical equation for the reaction involving potassium ferrocyanide (K₄[Fe(CN) ₆]) in a strongly acidic solution, resulting in the production of toxic hydrogen cyanide gas (HCN) .

a) K₄[Fe(CN) ₆] + 6 H⁺ → 4 K⁺ + [Fe(CN) ₆]²⁻ + 6 HCN + 6 H₂O
b) K₄[Fe(CN) ₆] + 6 H⁺ → 4 K⁺ + [Fe(CN) ₆]³⁻ + 6 HCN + 6 H₂O
c) 2 K₄[Fe(CN) ₆] + 12 H⁺ → 8 K⁺ + 2 [Fe(CN) ₆]²⁻ + 12 HCN + 12 H₂O
d) 3 K₄[Fe(CN) ₆] + 18 H⁺ → 12 K⁺ + 3 [Fe(CN) ₆]³⁻ + 18 HCN + 18 H₂O