Tìm nguyên hàm
$\int{{\frac{{\sin x}}{{1-{{{\cos }}^{2}}x}}dx}}.$
A. $\displaystyle -\ln \left| {\frac{{\cos x-1}}{{\cos x+1}}} \right|+C.$
B. $\displaystyle \ln \left| {\frac{{\cos x-1}}{{\cos x+1}}} \right|+C.$
C. $\displaystyle -\frac{1}{2}\ln \left| {\frac{{\cos x-1}}{{\cos x+1}}} \right|+C.$
D. $\displaystyle \frac{1}{2}\ln \left| {\frac{{\cos x-1}}{{\cos x+1}}} \right|+C.$