Sound wave, ocean wave, wave on a rope, stadium wave. What dosent belong and why?

The stadium wave does not belong

Explanation:

The stadium wave (known as the Mexican wave in the anglosphere outside North America) is an example of metachronal rhythm achieved in a packed stadium when successive groups of spectators briefly stand, yell, and raise their arms. Immediately upon stretching to full height, the spectator returns to the usual seated position. Sound waves, ocean waves, and waves on a sting are all examples of waves traveling through mediums, unlike the stadium wave, which is just a tradition in a stadium for sports.