A pebble is dropped in a pond. Which best describes the type of wave seen here?

When the rock first hits the surface of the water, it lets out a sharp peak in pressure. The rock then feels the force of the impact, and vibrates at its own natural frequency. Then it travels into the water, pulling bubbles along with it. Those bubbles are initially deformed, and they vibrate as they try to reach their equilibrium shape. Then those bubbles pop on the surface (though that's barely audible). All of this happens in an instant, and makes the "ploop" sound you hear when you drop a rock.