The degree of unsaturation of the compound shown (the nitro group counts as one N=O pi bond, N taken as trivalent in the formula method) equals that of the molecular formula

Answer: C

The compound shown is nitrobenzene,

C X_{6} H X_{5} NO X_{2}

: DBE

= (2 \times 6 + 2 + 1 - 5) /2 = 5

(ring 1, three C=C, one N=O). The formulas give

C X_{8} H X_{10}

C X_{7} H X_{8} O

C X_{8} H X_{8} O

5 and

C X_{6} H X_{12}

1, so

C X_{8} H X_{8} O

matches.