Answer
a. The wave is propagating in the +z direction.
b. The wave is propagating in the +z direction.
c. The wave is propagating in the -y direction.
d. The wave is propagating in the -x direction.
Work Step by Step
In each case, the direction of propagation is given by the direction of $\vec{E} \times \vec{B}$. As expected, the direction is perpendicular to the plane containing the vectors $\vec{E}$ and $\vec{B}$.
