$\left(\mathrm{CH}_{2} \mathrm{CO}\right)_{2} \mathrm{O}+\mathrm{RMgX} \stackrel{\mathrm{H}_{2} \mathrm{O}}{\longrightarrow} ?$

• A

  $\mathrm{ROOC}\left(\mathrm{CH}_{2}\right) \mathrm{COOR}$
• Correct answer
  B

  $\mathrm{RCOCH}_{2} \mathrm{CH}_{2} \mathrm{COOH}$
• C

  RCOOR
• D

  RCOOH

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