In a two-dimensional flow fluid, if a velocity potential function $$\phi$$ exists which satisfies the relation $$\frac{\partial^{2} \phi}{\partial x^{2}}+\frac{\partial^{2} \phi}{\partial y^{2}}$$=0 then the flow is

A

steady incompressible

B

steady laminar and incompressible

C

irrotational and incompressible

D

turbulent and incompressible