If f(x)=1x2+1f(x) = \frac{1}{x^2+1}f(x)=x2+11, what is the range of f(x)f(x)f(x)?
(0,1](0, 1](0,1]
(0,∞)(0, \infty)(0,∞)
[0,1][0, 1][0,1]
(−1,1](-1, 1](−1,1]