Geo-Scientist Prelims 2025 Chemistry Q102: The major product formed in the following reaction is :

The major product formed in the following reaction is :

1. (a) cis-fused cyclopentene γ-lactone with C=C next to the O-bearing ring-fusion carbon (2-oxabicyclo[3.3.0]oct-7-en-3-one type)
2. (b) cis-fused cyclopentene γ-lactone with C=C next to the CH-bearing ring-fusion carbon
3. (c) bicyclic γ-lactone with C=C at the ring fusion conjugated to C=O (butenolide)
4. (d) bicyclic γ-lactone with C=C at the ring fusion bearing the ring O (enol lactone)