$\begin{array}{1 1} (A)\quad(4x+6y+5)\;dy-(3y+2x+4)\;dx = 0\\(B)\quad(xy)\;dx-(x^3+y^3)\;dy = 0\\(C)\quad(x^3+2y^2)dx+2xy\;dy=0\\(D)\quad y^2dx+(x^2-xy-y^2)\;dy=0\end{array} $
