Two polaroids are placed in the path of an unpolarised light beam of intensity $I_0$ such that no light is emitted from the second polaroid. If a third polaroid,whose polarisation axis makes an angle $\theta$ with that of the first polaroid,is placed between the polaroids,then the intensity of light emerging from the last polaroid is

• A
  $\left(\frac{I_0}{8}\right) \sin^2 2\theta$
• B
  $\left(\frac{I_0}{4}\right) \sin^2 2\theta$
• C
  $\left(\frac{I_0}{2}\right) \cos^2 \theta$
• D
  $I_0 \cos^2 \theta$