When the energy of the incident radiation is increased by $20%$, the kinetic energy of the photoelectrons emitted from a metal surface increased from emitted 0.5 eV to 0.8eV. The work function of the metal is :

Question

( A ) 1.5 eV
( B ) 1.0 eV
( C ) 1.3 eV
( D ) 0.65 eV