Issues with Low Frequency

Q. An electro-magnetic wave is propagating in a medium with a velocity $\overrightarrow{v}=v\hat{i}$ . The instantaneous oscillating electric field of this electromagnetic wave is along $+y$ axis. Then, the direction of oscillating magnetic field of the electromagnetic wave will be along

1. –$z$ direction
2. +$z$ direction
3. –$y$ direction
4. –$x$ direction