The differential equation of all the lines in the xy-plane is

• A.                 \[\frac{dy}{dx}-x=0\]          
• B.                 \[\frac{{{d}^{2}}y}{d{{x}^{2}}}-x\frac{dy}{dx}=0\]
• C.                 \[\frac{{{d}^{2}}y}{d{{x}^{2}}}=0\]        
• D.                 \[\frac{{{d}^{2}}y}{d{{x}^{2}}}+x=0\]