What is the speed of all types of electromagnetic radiation in a vacuum? What is it called?

• A
  $3.0 \times 10^{8} \text{ m s}^{-1}$,Speed of light $(c)$
• B
  $3.0 \times 10^{10} \text{ m s}^{-1}$,Speed of sound
• C
  $3.0 \times 10^{6} \text{ m s}^{-1}$,Velocity of particles
• D
  $3.0 \times 10^{5} \text{ m s}^{-1}$,Wave velocity