The oscillating electric and magnetic field vectors of an electromagnetic wave are along

• A

  the same direction and in same phase.
• B

  the same direction but have a phase difference of $90^{\circ}$.
• Correct answer
  C

  mutually perpendicular directions and are in same phase.
• D

  mutually perpendicular directions but have a phase difference of $90^{\circ}$.

Hence, the correct answer is option: 'C'.