Which expression is equivalent to x2−y2x3−y3⋅x2+xy+y2x+y\frac{x^2-y^2}{x^3-y^3} \cdot \frac{x^2+xy+y^2}{x+y}x3−y3x2−y2⋅x+yx2+xy+y2?
1
x−yx+y\frac{x-y}{x+y}x+yx−y
1x−y\frac{1}{x-y}x−y1
x+yx−y\frac{x+y}{x-y}x−yx+y