Tìm nguyên hàm $\int{{\frac{1}{{x(x-3)}}dx}}.$
A. $\frac{1}{3}\ln \left| {\frac{x}{{x-3}}} \right|+C.$
B. $\frac{{-2}}{3}\ln \left| {\frac{{x-3}}{x}} \right|+C.$
C. $\frac{{-1}}{3}\ln \left| {\frac{{x-3}}{x}} \right|+C.$
D. $\frac{1}{3}\ln \left| {\frac{{x-3}}{x}} \right|+C.$