$\text{ OF}$ and ${\mathrm{F}}_2$ can be compared in terms of:

The absence of an unpaired electron in the MO diagram above indicates that the molecule below is not paramagnetic. 

${\mathrm{F}}_2$ is therefore not paramagnetic.

Because OF is paramagnetic and ${\mathrm{F}}_2$ is diamagnetic, it is more stable when splitting into atoms.

Hence correct option is C.