Carboxylic Acids And Its Derivatives

In a reaction,

\(\left(\mathrm{CH}_3\right)_2 \mathrm{CHMgBr}+\mathrm{CO}_2 \xrightarrow[\text { ether }]{\text { dry }} \mathrm{A} \xrightarrow[\text { dilHCl }]{\mathrm{H} . \mathrm{OH}} \mathrm{~B} \text {. }\)

Find the product ' B ' of above reaction.