Consider the following reaction,
$2H_{2(g)} + 2NO_{(g)} \rightarrow N_{2(g)} + 2H_2O_{(g)}$
which follows the mechanism given below:
$2NO_{(g)} \underset{k_{-1}}{\stackrel{k_1}{\rightleftharpoons}} N_2O_{2(g)}$ (fast equilibrium)
$N_2O_{2(g)} + H_{2(g)} \stackrel{k_2}{\rightarrow} N_2O_{(g)} + H_2O_{(g)}$ (slow reaction)
$N_2O_{(g)} + H_{2(g)} \stackrel{k_3}{\rightarrow} N_{2(g)} + H_2O_{(g)}$ (fast reaction)
The order of the reaction is

• A
  $1$
• B
  $2$
• C
  $3$
• D
  $4$