"A" obtained by Ostwald's method involving air oxidation of NH$$_3$$, upon further air oxidation produces "B". "B" on hydration forms an oxoacid of Nitrogen along with evolution of "A". The oxoacid also produces "A" and gives positive brown ring test

A

NO$$_2$$, N$$_2$$O$$_5$$

B

NO$$_2$$, N$$_2$$O$$_4$$

C

NO, NO$$_2$$

D

N$$_2$$O$$_3$$, NO$$_2$$