Concept:To form the differential equation, eliminate the arbitrary constant c by differentiating the given equation.Explanation:Given: 3y=3x+cCubing both sides removes the cube root:(3y)3=x+c27y3=x+cDifferentiate both sides with respect to x:dxd(27y3)=dxd(x+c)Using the chain rule:81y2dxdy=1Therefore,dxdy=81y21Answer:The differential equation is dxdy=81y21, which matches Option C.