Energy required to remove an electron from aluminium surface is 4.3 V. If light of wavelength 2000 Å falls on the surface, the velocity of the fastest electron ejected from the surface will be
A. `8.4 xx 10^(5) m//sec`
B. `7.4 xx 10^(5) m//sec`
C. `6.4 xx 10^(5) m//sec`
D. `8.4 xx 10^(6) m//sec`