Which of the following sets of equations represent possible three dimensional incompressible flow cases?

(a) \(u=2 y^{2}+2 x z ; v=-2 x y+6 x^{2} y z ; w=3 x^{2} z^{2}+x^{3} y^{4}\)

(b) \(u=x y z t ; v=-x y z z^{2} ; w=z^{2}\left(x t^{2}-y t\right)\)

(c) \(u=x^{2}+2 y+z^{2} ; v=x-2 y+z ; w=-2 x z+y^{2}+2 z\)