Answer: She should find that the speed of sound travels fastest in liquid water. It would travel slowest in water vapor.
In most substances, sound travels faster in solids than it does in liquids.
Water, however, is consisted of hydrogen bonds. These bonds cause water to expand when it is froze. So, water is actually less dense in solid form. In liquid form, water is denser than it is in solid form. Saying that, sound would travel fastest in liquid water because there are more molecules to oscillate and therefore conduct sound. This is all because water is denser in liquid form as opposed to solid form. Therefore, liquid water conducts sound better than solid water or water vapor.