Ans:(a) and (d)

Explanation:

Given that electric field vector of an electromagnetic wave travels in vacuum along   z – direction is

$\overrightarrow{\text{E}}=\left({\text{E}}_1+{\text{E}}_2 \right) \cos \left(kz-\omega t\right)\_\_\_\_\_\_\_\left(i\right)$ 

The magnetic of the electric and magnetic fields in an electromagnetic wave are related as

$\begin{array}{l}{\text{B}}_0=\frac{E_0}{C}\\ \therefore \overrightarrow{\text{B}}=\frac{\overrightarrow{E}}{C}\\ \overrightarrow{\text{B}}=\frac{{\text{E}}_1+{\text{E}}_2 }{C}\cos \left(kz-\omega t\right)\\ \overrightarrow{\text{B}}=\frac{1}{C}\left({\text{E}}_1+{\text{E}}_2 \right) \cos \left(kz-\omega t\right)\_\_\_\_\_\left(ii\right)\end{array}$ 

(a)

Also E and B are perpendicular to each other and the propagation of electromagnetic wave is perpendicular to E as well as B, so the given electromagnetic wave is plane polarized (d)