What Does an S-Wave Do to the Rock It Passes

Question 66
Multiple Choice

What does an S-wave do to the rock it passes through? A)It lifts it up and down in a wavelike motion (perpendicular to the advancing wave front), distorting the rock's shape while holding its volume (and density)constant. B)It alternately compresses and expands the rock (like the bellows of an accordion)along the direction of the advancing wave. C)It causes the rock to wiggle from side to side as the wave advances. D)It causes the rock to move in little vertical circles as the wave advances.