A polaroid is placed at ${45}^{\circ }$ to an incoming light of intensity ${\mathrm{I}}_0.$ Now the intensity of light passing through polaroid after polarisation would be

• A

  ${\mathrm{I}}_0$

• B

  ${\mathrm{I}}_0/2$

• C

  ${\mathrm{I}}_0/4$

• D

  Zero