Which expression is equivalent to (x1/2+y1/2)2−(x1/2−y1/2)2(x^{1/2} + y^{1/2})^2 - (x^{1/2} - y^{1/2})^2(x1/2+y1/2)2−(x1/2−y1/2)2?
4xy4\sqrt{xy}4xy
2x+2y2x+2y2x+2y
2xy2\sqrt{xy}2xy
x+yx+yx+y