$A$ uniform magnetic field is restricted within a region of radius $r$. The magnetic field changes with time at a rate $\frac{d\vec{B}}{dt}$. Loop $1$ of radius $R > r$ encloses the region,and loop $2$ of radius $R$ is outside the region of the magnetic field as shown in the figure. Then the $e.m.f.$ generated is:

• A
  $-\frac{d\vec{B}}{dt}\pi R^2$ in loop $1$ and zero in loop $2$
• B
  $-\frac{d\vec{B}}{dt}\pi r^2$ in loop $1$ and $0$ in loop $2$
• C
  zero in loop $1$ and zero in loop $2$
• D
  $-\frac{d\vec{B}}{dt}\pi r^2$ in loop $1$ and $-\frac{d\vec{B}}{dt}\pi r^2$ in loop $2$