Which among the following has highest boiling point?

Boiling points of isomeric alcohols are determined by intermolecular forces, particularly hydrogen bonding and van der Waals interactions.

All C$_{4}$H$_{10}$O isomers exhibit hydrogen bonding due to the -OH group. Van der Waals forces depend on molecular surface area, which decreases with branching.

Butan-1-ol (A) is straight-chain with maximum surface area. Butan-2-ol (C) is straight-chain but secondary. 2-Methylpropan-1-ol (B) has one branch. 2-Methylpropan-2-ol (D) is highly branched tertiary.

Boiling points decrease with increased branching: A (117.7 $^{\circ}$C) $>$ C (99.5 $^{\circ}$C) $>$ B (107.9 $^{\circ}$C) $>$ D (82.5 $^{\circ}$C).