d

The maximum energy is corresponding to high frequency is correspond to 

$ \omega = 6.28\times 10^7 c $

$\Rightarrow \nu = \frac{6.28\times 10^7 c}{2\pi} = 3\times 10^{15} $ 

$\Rightarrow E = h\nu = 6.62\times 10^{-34}\times 3 \times 10^15 = 19.86 \times 10^{-19} J =\frac{ 19.86 \times 10^{-19} }{1.6\times 10^{-19}} = 12.42eV$

$ K_{max} = 12.42 - 4.7 = 7.72eV$