A chemist studies the vapor-phase formation of a hypothetical coating precursor according to the overall reaction

\[ \text{AX(g)}+\text{B(g)}+\text{X(g)}\rightarrow\text{ABX}_2\text{(g)} \]

Initial-rate measurements at constant temperature give the following rate law.

\[ \text{rate}=k_{\mathrm{obs}}\dfrac{[\text{AX}][\text{B}]}{[\text{X}]} \]

The chemist proposes the mechanism below. Each step is elementary, and step \(1\) rapidly reaches equilibrium before the slow step occurs.

Step	Proposed elementary process
\(1\)	\(\text{AX(g)}\rightleftharpoons\text{A(g)}+\text{X(g)}\), fast equilibrium, \(K_c=\dfrac{k_1}{k_{-1}}\)
\(2\)	\(\text{A(g)}+\text{B(g)}\rightarrow\text{AB(g)}\), slow
\(3\)	\(\text{AB(g)}+\text{X(g)}\rightarrow\text{ABX(g)}\), fast
\(4\)	\(\text{ABX(g)}+\text{X(g)}\rightarrow\text{ABX}_2\text{(g)}\), fast

Which of the following correctly evaluates whether the proposed mechanism is consistent with both the overall reaction and the observed rate law?