A uniform magnetic field is restricted within a region of radius $r$. The field changes with time at a rate $dB/dt$. Loop 1 of radius $R>r$ encloses the region and loop 2 of radius $R$ is outside the region. The e.m.f. generated is:

1. A
   $-\pi r^2\frac{dB}{dt}$ in loop 1 and zero in loop 2
2. B
   zero in loop 1 and zero in loop 2
3. C
   $-\pi r^2\frac{dB}{dt}$ in loop 1 and $-\pi r^2\frac{dB}{dt}$ in loop 2
4. D
   $-\pi R^2\frac{dB}{dt}$ in loop 1 and zero in loop 2