What is the general form of second order non-linear partial differential equations (x and y being independent variables and z being a dependent variable)?

• A. (F(x,y,z, frac{ z}{ x}, frac{ z}{ y}, frac{ ^2 z}{ x^2}, frac{ ^2 z}{ y^2}, frac{ ^2 z}{ x y})=0 )
• B. (F(x,z, frac{ z}{ x}, frac{ z}{ y}, frac{ ^2 z}{ x^2}, frac{ ^2 z}{ y^2})=0 )
• C. (F(y,z, frac{ z}{ x}, frac{ z}{ y})=0 )
• D. F(x,y)=0