The reaction sequence proceeds as follows:
The reagent NaBH4 is a mild reducing agent that selectively reduces the aldehyde group (−CHO) to a primary alcohol (−CH2OH). The lactam (cyclic amide) ring remains unaffected.
Heating with aqueous NaOH causes the base-catalyzed hydrolysis of the lactam ring. The amide bond breaks, forming a carboxylate salt (−COO−) and a secondary amine (−NH−).
Acidification with H3O+ protonates the carboxylate ion to form a carboxylic acid (−COOH).
The final product is an open-chain amino acid derivative with the structure HOOC−CH2−CH2−CH2−CH2−NH−CH(CH3)−CH2OH. This matches the structure given in option (C).
Answer: 




