The correct option is C a2−πa24
As we can see the figure given in the question is a circle inscribed in a square.
So for the area of the shaded region, we have to subtract the area of the circle from area of square.
Area of the square = (side)2=a2
Here we know the diameter of the circle from given figure, which is a.
⇒ Radius of the circle = a2
⇒ Area of the circle = π×(radius)2=π×(a2)2=πa24
⇒Area of the shaded portion = a2−πa24
Hence, option c is correct.