An em wave id propagating in a medium with a velocity $\overrightarrow{V} = V \hat{i}$. The instantaneous oscillating electric field of this em wave is along +y axis. Then the direction of oscillating magnetic field of the em wave will be along

Question

( A ) $+z$ direction
( B ) $-x$ direction
( C ) $-y$ direction
( D ) $-z$ direction