Select the correct statement about the mathematical character of the Navier-Stokes equation and the boundary layer x-momentum equation.
1) Both the Navier-Stokes equation and the boundary layer x-momentum equation are elliptic.
2) Both the Navier-Stokes equation and the boundary layer x-momentum equation are linear.
3) Both the Navier-Stokes equation and the boundary layer x-momentum equation are parabolic.
4) The Navier-Stokes equation is elliptic, and the boundary layer x-momentum equation is parabolic.
5) The Navier-Stokes equation is parabolic, and the boundary layer x-momentum equation is elliptic.