Which expression has a horizontal asymptote at y=0y = 0y=0?
x−1x\frac{x-1}{x}xx−1
x2x−1\frac{x^2}{x-1}x−1x2
5x2−4\frac{5}{x^2-4}x2−45
x3x+1\frac{x^3}{x+1}x+1x3