Carboxylic Acids And Its Derivatives

Identify the product ' B ' in following reaction.

Dry ice $\xrightarrow[\text { dry ether }]{\mathrm{CH}_3 \mathrm{MgBr}} \mathrm{A} \xrightarrow{\mathrm{H}_3 \mathrm{O}^{+}} \mathrm{B}$