The compound shown is subjected to Birch reduction ($\mathrm{Na}$, liquid $\mathrm{NH}{}_3$, ethanol) and then neutralised. Which structure is the major product?

The compound is benzoic acid. An electron-withdrawing group such as $\mathrm{COOH}$ is attached to an sp3 carbon in the Birch product (reduction at the ipso and para carbons), giving cyclohexa-2,5-diene-1-carboxylic acid. The isomers with the acid on a vinyl carbon are the donor-substituent pattern.