Concept:Rewrite as a linear differential equation and use an integrating factor to solve.Explanation:Divide the given equation by x2: dxdy−xy=x21This is of the form dxdy+Py=Q, where P=−x1 and Q=x21.Integrating factor:I.F.=e∫−x1dx=e−lnx=x1Multiply the equation by x1:x1dxdy−x2y=x31The left side becomes dxd(xy), so:dxd(xy)=x31Integrate both sides:xy=∫x−3dx=−2x21+cMultiply by x:y=cx−2x1Multiply by 2x and rearrange:2xy−2cx2+1=0Answer:2xy−2cx2+1=0Therefore, the correct option is C.