Ok I tried my best here;
What do we need to find is A(shaded region) = A(circle) - A(square)
A(circle) = r^2*pi
A(square) = s^2
We are given the circumference of the circle, which also operates as the diagonal of the square.
The circumference is 2*pi*sqrt(x)
The circumference normally is diameter * pi
Since the circumference given already has pi in it, the diameter must be 2*sqrt(x)
Since the radius is diameter divided by 2 then the radius would be the sqrt(x)
So the area of the circle would be sqrt(x)^2 * pi which would be x*pi
Okay now the square;
the diameter of the circle is the diagonal of the square, splitting it in two 45-45-90 triangles.
We know that 45-45-90 triangles have a ratio of x : x : x*sqrt(2)
Since the diagonal is already given which is 2*sqrt(x), would make the side the same as 2*x since, sqrt(2) * 2 = 2 and sqrt(x) * x = x
Therefore the answer should be B.
Hope i'm right