函数f(x)=(x-1)/(x+1)的反函数是().
A.f-1(x)=(x-1)/(x+1)
B.f-1(x)=(1-x)/(1+x)
C.f-1(x)=(x+1)/(x-1)
D.f-1(x)=(1+x)/(1-x)
正确答案是D