Answer: Option a.
Step-by-step explanation:
For an idealistic electromagnetic wave, both magnetic and electric fields are perpendicular to the travel direction of the wave.
Here we know that the electric field points to negative y-direction, and the magnetic field points to negative z-direction.
Then the wave must be traveling in the x-axis direction.
Then the correct option is a; +x direction (this is the only option that has the x-direction, then it is easy to identify it as the correct option)