The Reaction NO₂(g) +CO(g) $\rightarrow$ NO(g) +CO₂(g) Is Thought to Occur by the Following Mechanism

The reaction NO₂(g) +CO(g) $\rightarrow$ NO(g) +CO₂(g) is thought to occur by the following mechanism:
Step 1: NO₂(g) +NO₂ (g) $\rightarrow$ NO₃(g) + NOg)
Step 2: NO₃(g) + CO(g) $\rightarrow$ NO₂(g) +CO₂(g)
Which of the following species is an intermediate?

A) NO₂
B) NO
C) NO₃
D) CO₂
E) This mechanism has no intermediates.