A total charge Q is uniformly distributed over a non conducting ring of radius r. There is a time varying magnetic field perpendicular to its plane and changing at the uniform rate of $$\frac{dB}{dt}$$. The magnitude of induced tangential electric field E on ring is

A

$$r\frac{dB}{dt}$$

B

$$r^2\frac{dB}{dt}$$

C

$$\frac{1}{2}r\frac{dB}{dt}$$

D

$$\frac{1}{2}r^2\frac{dB}{dt}$$