The same progressive wave is represented by two graphs I and II. Graph I shows how the displacement 'y' varies with the distance x along the wave at a given time. Graph II shows how y varies with time t at a given point on the wave. The ratio of measurements AB to CD, marked on
the curves, represents:

• A

  wave number k

• B

  wave speed v

• C

  frequency v

• D

  angular frequency $\mathrm{\omega }$