Which of the following compounds has the highest boiling point?

Boiling point depends on the strength of intermolecular forces.

$\text{CH}_3\text{-CH}_2\text{-CH}_3$ is non-polar and has only weak London dispersion forces.

$\text{CH}_3\text{-O-CH}_3$ and $\text{CH}_3\text{-Cl}$ are polar and have dipole-dipole interactions, but their dipole moments are relatively small.

$\text{CH}_3\text{-CN}$ has a highly polar $-\text{CN}$ group, resulting in a very high dipole moment and strong dipole-dipole interactions.

Due to the strongest intermolecular forces, $\text{CH}_3\text{-CN}$ has the highest boiling point among the given compounds.

Answer: $\text{CH}_3\text{-CN}$