In which one of the following equilibria, Kp ≠ Kc?

• A. 2C (s) + O2 (g) ⇌ 2CO (g)
• B. 2HI (g) ⇌ H2 (g) + I2 (g)
• C. NO (g) + SO2 (g) ⇌ NO (g) + SO3 (g)
• D. 2NO (g) ⇌ N2 (g) + O2 (g)