$A$ thin ring of radius $R$ metre has charge $q$ coulomb uniformly spread on it. The ring rotates about its axis with a constant frequency of $f$ revolution/s. The value of magnetic induction at the centre of the ring in $\text{Wb/m}^2$ is ($\mu_0$ = permeability of free space)

• A
  $\frac{\mu_0 qf}{2R}$
• B
  $\frac{\mu_0 q}{2\pi R}$
• C
  $\frac{\mu_0 qf}{2\pi R}$
• D
  $\frac{\mu_0 q\pi}{2fR}$