A photosensitive metallic surface has work function hvo. If photons of energy 2hvo, fall on this surface. the electrons come out with a maximum velocity of 4 x 106 m/s. When the photon energy is increased to 5hvo, then maximum velocity of photoelectrons will be
(a) 2 x 107 m/s
(b) 2 x 106 m/s
(c) 8 x 106 m/s
(d) 8 x 105 m/s