A Proposed Mechanism for the Reduction of Nitrogen as NO $\rightarrow$

A proposed mechanism for the reduction of nitrogen as NO by hydrogen is:
Step 1: H₂(g) + 2 NO(g) $\rightarrow$ N₂O(g) + H₂O(g)
Step 2: N₂O(g) + H₂(g) $\rightarrow$ N₂(g) +H₂O(g)
What is the molecularity of step 1?

A) unimolecular
B) bimolecular
C) termolecular
D) zero molecular spontaneous)
E) More information is needed.