Equation of a progressive wave is given by $\mathrm{y}=\mathrm{a}\mathrm{sin\pi }\left[\frac{\mathrm{t}}{2}-\frac{\mathrm{x}}{4}\right],$ where t is in seconds and x is in meters. The distance through which the wave moves in 8 sec is (in meter) 

• A

  8

• B

  16

• C

  2

• D

  4