A charge Q is placed at the centre of a circle of radius R. The work done in moving a charge q from A to B so as to complete a semi-circle is :

• A

  Zero

• B

  $\frac{\mathrm{Qq}}{4{\mathrm{\epsilon }}_0\mathrm{R}}$

• C

  $\frac{\mathrm{Qq}}{2{\mathrm{\epsilon }}_0\mathrm{R}}$

• D

  $\frac{\mathrm{Qq}}{4{\mathrm{\epsilon }}_0{\mathrm{R}}^2}$