If x,y,zx, y, zx,y,z are in AP, which of the following is equivalent to x2+z2x^2 + z^2x2+z2?
2y2+2d22y^2 + 2d^22y2+2d2
y2+d2y^2 + d^2y2+d2
2y2−2d22y^2 - 2d^22y2−2d2
4y2−d24y^2 - d^24y2−d2