$A$ disc of radius $r$ carrying a positive charge $q$ is rotating with an angular speed $\omega$ in a uniform magnetic field $B$ about a fixed axis as shown in the figure,such that the angle made by the axis of the disc with the magnetic field is $\theta$. The torque applied by the axis on the disc is:

• A
  $\frac{q\omega r^2 B \sin \theta}{2}$,clockwise
• B
  $\frac{q\omega r^2 B \sin \theta}{4}$,anticlockwise
• C
  $\frac{q\omega r^2 B \sin \theta}{2}$,anticlockwise
• D
  $\frac{q\omega r^2 B \sin \theta}{4}$,clockwise