单项选择题

设4/(1-x2)·f(x)=d/dx[f(x)]2,且f(0)=0,则f(x)等于:()

A.(1+x)/(1-x)+c
B.(1-x)/(1+x)+c
C.1n|(1+x)/(1-x)|+c
D.1n|(1-x)/(1+x)|+c