Answer
case 1, positive x direction
case 2, positive z direction
case 3, negative x direction
Work Step by Step
According to the right hand rule from figure 1, the propagation of the wave is along the x direction because the electric field is along the y direction and the magnetic field is along the z direction.
In the second case, the propagation of the wave is along the +z direction because the electric field is along the x direction and the magnetic field is along the y direction.
In the third case, the propagation of the wave is along the -x direction because the electric field is along the z direction and the magnetic field is along the y direction.