Problem Fifteen. Electrons are ejected from a metallic surface with speeds ranging up to $2\mathrm{.}50$ x $108$ m$/$s when light with a wavelength of m $121050.1$ is used. $($THIS IS AN EXAM QUESTION.$)23.$ Find the cutoff frequency for this surface in units of $1019$ Hz$.($A$)1\mathrm{.}33($B$)2\mathrm{.}67($C$)9\mathrm{.}95($D$)4\mathrm{.}38($E$)5\mathrm{.}38$