If f(x)=x3−6x2+9xf(x) = x^3 - 6x^2 + 9xf(x)=x3−6x2+9x, on what interval is the function decreasing?
(1,3)(1, 3)(1,3)
(0,1)(0, 1)(0,1)
(3,∞)(3, \infty)(3,∞)
(−∞,1)(-\infty, 1)(−∞,1)