Some reactions of NO$$_2$$ relevant to photochemical smog formation are

Identify A, B, X and Y

A

X = [O], Y = NO, A = O$$_2$$, B = O$$_3$$

B

X = N$$_2$$O, Y = [O], A = O$$_3$$, B = NO

C

X = $$\frac{1}{2}$$O$$_2$$, Y = NO$$_2$$, A = O$$_3$$, B = O$$_2$$

D

X = NO, Y = [O], A = O$$_2$$, B = N$$_2$$O$$_3$$