The displacement y of a wave travelling in the x-direction is given by $\mathrm{y} = {10}^{-4}\sin (600\mathrm{t}-2\mathrm{x}+\frac{\mathrm{\pi }}{3})$ metres, where x is expressed in metres and t in seconds. The speed of the wave-motion in ${\mathrm{ms}}^{-1}$, is

• A

  200

• B

  300

• C

  600

• D

  1200