Determine the range of the function f(x)=exex+1+e−xe−x+1f(x) = \frac{e^x}{e^x + 1} + \frac{e^{-x}}{e^{-x} + 1}f(x)=ex+1ex+e−x+1e−x.
(0,1)(0, 1)(0,1)
(0,2)(0, 2)(0,2)
111
(1,2)(1, 2)(1,2)