The major product formed in the following reaction

Explanation: -

The reaction will occur as follows: -

Step 1: the diethyl succinate with loses an acidic α-hydrogen in reaction with base t-BuOK, to give a nucleophile.

Step 2: In the second step this nucleophile will attack the electron-deficient carbonyl carbon of benzaldehyde. To give a condensation product

Step 3: In the second part of the reaction acid is added, we know that in an acidic medium alcohols give a dehydration reaction as follows: 

Step 4: hydrolysis of conjugated ester in the presence of acidic medium

Conclusion:-

Hence, the correct option is 1.