The bond angle $\mathrm{H} - \mathrm{X} - \mathrm{H}$ is the greatest in the compound:

${\mathrm{CH}}_4$ has the greatest $\mathrm{H} - \mathrm{C} - \mathrm{H}$ bond angle. The other molecules have lone pair(s) of electrons. Due to lone pair-bonding pair repulsion, the angle $\mathrm{H} - \mathrm{X} - \mathrm{H}$ is decreased from the expected bond angle of tetrahedral structure. i.e. $109° 28\text{'}.$