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
• E. ?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