The solution of the differential equation \[x\,dy-y\,dx=(\sqrt{{{x}^{2}}+{{y}^{2}})}dx\]is

• A.                 \[y-\sqrt{{{x}^{2}}+{{y}^{2}}}=c{{x}^{2}}\]      
• B.                 \[y+\sqrt{{{x}^{2}}+{{y}^{2}}}=c{{x}^{2}}\]
• C.                 \[y+\sqrt{{{x}^{2}}+{{y}^{2}}}+c{{x}^{2}}=0\]               
• D.                 None of these