The Figure Shows a Uniform Magnetic Field That Is Normal $\pi$

Multiple Choice

The figure shows a uniform magnetic field that is normal to the plane of the conducting loop of resistance R. Note: the area of the non-circular portion of the circuit is negligible compared to that of the loop.
-Suppose that the radius of the loop is 0.500 m. At what rate must B change with time if the emf induced in the loop is $\pi$ volts?

A) 12.0 T/s
B) 18.8 T/s
C) 24.0 T/s
D) 37.7 T/s
E) 49.2 T/s