Energy required to remove an electron from aluminium surface is 4.2 eV. If light of wavelength 2000 Å falls on the surface, the velocity of the fastest electron ejected from the surface will be [AMU 1999]

• A.            \[8.4\times {{10}^{5}}m/sec\]                                          
• B.            \[7.4\times {{10}^{5}}m/sec\]
• C.            \[6.4\times {{10}^{5}}m/sec\]                                          
• D.            \[8.4\times {{10}^{6}}m/sec\]