21. For the reaction CH3CHCH2(g) + HCl(g) → CH3CHC1CH3(g) a possible mechanism is 2 HCl ⇌(HCl)2 (rate constant: k₁ and k-1, fast equilibrium) CH3CHCH2 + HCl ⇌Complex (rate constant: k2 and , fast equilibrium) Complex + (HCl)2 →CH3CHCICH3 + 2HCl (rate constant k3, slow) What's the rate law for this reaction? (A)(B) (C) (D) (E)