The reaction of hydrogen and iodine monochloride is given as: $H_2(g) + 2ICl(g) \to 2HCl(g) + I_2(g)$. This reaction is of first order with respect to $H_2(g)$ and $ICl(g)$. The following mechanisms were proposed:

Mechanism A: $H_2(g) + 2ICl(g) \to 2HCl(g) + I_2(g)$ (elementary)

Mechanism B:
$H_2(g) + ICl(g) \to HCl(g) + HI(g)$ (slow)
$HI(g) + ICl(g) \to HCl(g) + I_2(g)$ (fast)

Which of the above mechanism(s) can be consistent with the given information about the reaction?