The crowd in a stadium creates a wave traveling across the stands by having people stand up and then sit down one after another. the people move up and down creating the appearance of a wave moving across the stadium. this type of wave is best described as a) transverse wave b) compression wave c) elliptical wave d) electromagnetic wave

The correct option is: (A) Transverse Wave

Explanation:
Transverse wave is a wave in which the medium vibrates at right angles to the direction of its propagation.

In this case, consider the crowd as the medium and the perceived motion of the wave as the propagation. When the crowd moves up and down, the perceived wave be either from left to right or right to left. In either case, the crowd movement is perpendicular to the propagation of the wave. Imagine the crowd's up-down movement along y-axis and the perceived propagation of the wave along x-axis. Both axes are perpendicular to each other. Hence, the correct option is (A) Transverse wave.