The major product obtained in the following reaction is

The carbonyl group of the lactone becomes an aldehyde ($$-\text{CHO}$$).

The ring-fusion oxygen is protonated to form a hydroxyl group ($$-\text{OH}$$) remaining on the cyclopentadiene ring

The $$-\text{COOH}$$ group attached to the lower part of the ring is converted into a $$-\text{CHO}$$ group.

Option A correctly shows the addition of the hydroxyl group to the ring and the conversion of both the lactone and the carboxylic acid into aldehydes.