What are electromagnetic waves?

Which of the following pairs of components of $\overrightarrow{\mathrm{E}}$ and $\overrightarrow{\mathrm{B}}$ would generate a plane electromagnetic wave propagating along Z- direction?

$\left(\mathrm{i}\right){\mathrm{E}}_{\mathrm{x}},{\mathrm{B}}_{\mathrm{y}}\left(\mathrm{ii}\right){\mathrm{E}}_{\mathrm{y},}{\mathrm{B}}_{\mathrm{x}},\left(\mathrm{iii}\right){\mathrm{E}}_{\mathrm{x}},{\mathrm{B}}_{\mathrm{x}};\left(\mathrm{iv}\right){\mathrm{E}}_{\mathrm{y}},{\mathrm{B}}_{\mathrm{y}}\left(\mathrm{v}\right){\mathrm{E}}_{\mathrm{x}},{\mathrm{B}}_{\mathrm{z}};\left(\mathrm{vi}\right){\mathrm{E}}_{\mathrm{z}},{\mathrm{B}}_{\mathrm{x}.}$