An electromagnetic wave travels along z-axis. Which of the following pairs of space and time varying field would generate such a wave?

$W_x$ and $B_y$ would generate a plane EM wave travelling in z-direction, $\overrightarrow{E},\overrightarrow{B}$ and $\overrightarrow{k}$ from a right handed system $\overrightarrow{k}$ is along z-axis. As E is along z-axis and B is along y-axis. $\overrightarrow{i}\times \overrightarrow{j}=\overrightarrow{k}$ $\Rightarrow E_x\overrightarrow{i}\times B_y\overrightarrow{j}=C\overrightarrow{k}\text{ i.e., }$ E is along x-axis and B is along y-axis.