Which Equation Is NOT Required to Determine the Molar Solubility

Which equation is NOT required to determine the molar solubility of AgCN?

A) AgCN ⇋ Ag⁺ + CN⁻____________________K_sp = 2.2 × 10⁻¹⁶
B) H₂O + H₂O ⇋ H₃O⁺ + OH⁻ K_w = 1 × 10⁻¹⁴
C) [Ag⁺] = [CN⁻] + [HCN]
D) CN⁻ + H₂O ⇋ HCN + OH⁻ K_b = 1.6 × 10⁻⁵
E) HCN + H₂O ⇋ CN⁻ + H₃O⁺ K_a = 6.2 × 10⁻¹⁰