Let $l$ be the moment of inertia of a uniform square plate about an axis $AB$ that passes through its centre and is parallel to two of its sides. $CD$ is a line in the plane of the plate that passes through the centre of the plate and makes an angle $\theta$ with $AB$. The moment of inertia of the plate about the axis $CD$ is then equal to:

• A
  $l$
• B
  $l \sin^2 \theta$
• C
  $l \cos^2 \theta$
• D
  $l \cos^2 \frac{\theta}{2}$