Compound $\mathrm{X}$ on reaction with ${\mathrm{O}}_3$ followed by $\mathrm{Zn}/{\mathrm{H}}_2\mathrm{O}$ gives formaldehyde and $2$-methyl propanal as products. The compound $\mathrm{X}$ is:

• A

  $2$-Methylbut-$1$-ene
• B

  $2$-Methylbut-$2$-ene
• C

  Pent-$2$-ene
• Correct answer
  D

  $3$-Methylbut-$1$-ene

Hence, the correct answer is option: 'D'.