An electromagnetic wave travels in vacuum along $z$ direction:$E=(E_1\hat{i}-E_2 \hat{j})\cos (kz-\omega t)$. Choose the correct options from the following:

The associated magnetic field is given as$B=\frac{1}{c}(E_1\hat{i}-E_2 \hat{j})\cos (kz-\omega t)$

The associated magnetic field is given as 

$B=\frac{1}{c}(E_1\hat{i}+E_2 \hat{j}) \sin (kz-\omega t)$