A kite is inscribed in a rectangle. Everything outside of the kite is shaded. The points of the kite split the lengths of the rectangle into a length of 3x and x. The points of the kite split the height of the rectangle into lengths of x and x. The total length of the rectangle is 4 x and the height is 2 x. The figure shows a kite inside a rectangle. Which expression represents the area of the shaded region?

2x2
4x2
6x2
8x2