Question

Structure of (B) is :

• A.
• B.
• C.
• D.

Answer 1

The correct option is A

In the given substrate both aldehyde groups does not have a $\alpha$-hydrogen so it undergo cannizzaro reaction in presence of strong base. Also both aldehyde groups are in single substrate. Hence, it is a intramolecular cannizzaro reaction.
In this reaction one aldehyde group get reduced to alcohol and one oxidised to carboxylic acid.
Formed product on acidification form cyclic ester (lactones).