Marc and his brother Alex are swimming in a large lake. Marc comes up from being underwater and tells Alex there is a boat nearby. He heard it while underwater. Alex and Marc listen for the boat above the water, but they do not hear it. Which statement explains this phenomenon? O Air, a gas, does not transmit sound. O Sound requires a dense medium to travel through. O Sound travels faster in water, a liquid, than in air, a gas. ○ Sound has a higher frequency in water, a liquid, than in air, a gas, and can be heard better through water.