The function `f:R->(-1,1)` defined by `f(x)=(e^x-e^-x)/(e^x+e^-x)`, then

Options

A. `f(x)` is non-bijective
B. `f(x)` is a bijective function
C. `f^-1(x)=1/2log((1+x)/(1-x))`
D. `f(x)` is many one-one function