Light of wavelength $\lambda$ is incident on the surface of a metal having work function $\phi$, causing the emission of electrons. What is the maximum velocity of the emitted electrons? (Given: $c = \text{velocity of light}$, $h = \text{Planck's constant}$, $m = \text{mass of electron}$)

• A
  $\left[\frac{2(hc - \phi)}{m\lambda}\right]$
• B
  $\left[\frac{2(hc - \lambda\phi)}{m\lambda}\right]^{1/2}$
• C
  $\left[\frac{2(hc - \phi)}{m}\right]^{1/2}$
• D
  $\left[\frac{2(h\nu - \phi)\lambda}{mc}\right]$