A perfectly diamagnetic sphere has a small spherical cavity at its centre, which is filled with a paramagnetic substance. The whole system is placed in a uniform magnetic field  $\overrightarrow{B}$. Then the field inside the paramagnetic substance is :

• A

  $\overrightarrow{B}$

• B

  much large than  $\left|\overrightarrow{B}\right|$ but opposite to  $\overrightarrow{B}$

• C

  much large than  $\left|\overrightarrow{B}\right|$ and parallel to  $\overrightarrow{B}$

• D

  zero