Tính $F=\int{\ln \left( x+\sqrt{1+{{x}^{2}}} \right)dx}$ ?
A. $x\ln \left( x+\sqrt{1+{{x}^{2}}} \right)-\sqrt{1+{{x}^{2}}}+C.$
B. $-x\ln \left( x+\sqrt{1+{{x}^{2}}} \right)-\sqrt{1+{{x}^{2}}}+C.$
C. $\ln \left( x+\sqrt{1+{{x}^{2}}} \right)-\sqrt{1+{{x}^{2}}}+C.$
D. $x\ln \left( x+\sqrt{1+{{x}^{2}}} \right)+\sqrt{1+{{x}^{2}}}.$