When radiation is incident on a photoelectron emitter, the stopping potential is found to be 9 volts. If e/m for the electron is $1.8 \mathrm{x} {10}^{11}\mathrm{C} {\mathrm{kg}}^{-1}$  the maximum velocity of the ejected electrons is

• A

  $6\times {10}^5{\mathrm{ms}}^{-1}$

• B

  $8\times {10}^5{\mathrm{ms}}^{-1}$

• C

  $1.8\times {10}^6{\mathrm{ms}}^{-1}$

• D

  $1.8\times {10}^5{\mathrm{ms}}^{-1}$