The C-O-H bond angle in alcohols is slightly less than tetrahedral angle 109°28' due to

lone pair - lone pair repulsion

The correct answer is Option (2) → lone pair - lone pair repulsion

In alcohols, the oxygen atom is sp³ hybridized with two bond pairs (C–O and O–H) and two lone pairs, leading to a tetrahedral electron geometry (ideal angle 109°28'). The observed C–O–H bond angle is slightly less (e.g., ~108.9° in methanol) because lone pair–lone pair repulsion is stronger than bond pair–bond pair repulsion. This compresses the angle between the bonding pairs.