Tìm nguyên hàm
$\int{{\frac{{\sin x}}{{{{{\cos }}^{5}}x}}dx}}.$
A. $\frac{{-1}}{{4c\text{o}{{\text{s}}^{4}}x}}+C.$
B. $\frac{1}{{4c\text{o}{{\text{s}}^{4}}x}}+C.$
C. $\frac{1}{{4\text{si}{{\text{n}}^{4}}x}}+C.$
D. $-\frac{1}{{4\text{si}{{\text{n}}^{4}}x}}+C.$