If the Magnetic Field in an EM Wave Is in the X-Direction

Multiple Choice

If the magnetic field in an EM wave is in the x-direction and the electric field in the wave is in the y-direction, the wave is traveling in the

A) x-y plane.
B) direction halfway between the x- and y-directions.
C) z-direction.
D) x-direction.
E) negative z-direction.