Light of frequency $1.6 \times 10^{16} \ Hz$ falling on a metal plate emits electrons that have double the kinetic energy compared to the kinetic energy of electrons emitted when light of frequency $1.0 \times 10^{16} \ Hz$ falls on the same plate. The threshold frequency $(v_0)$ of the metal in $Hz$ is:

• A
  $1 \times 10^{15}$
• B
  $4 \times 10^{15}$
• C
  $3 \times 10^{15}$
• D
  $4 \times 10^{13}$