Which expression is equivalent to (x2+y2)2−(x2−y2)2(x^2+y^2)^2 - (x^2-y^2)^2(x2+y2)2−(x2−y2)2?
4x2y24x^2y^24x2y2
2x2y22x^2y^22x2y2
x4−y4x^4-y^4x4−y4
4xy4xy4xy