Scientists on a ship are using sonar to map the ocean floor. They send out a pulse at Point A that takes 4 seconds to return to the ship. At Point B, the sound pulse takes 8 seconds to return to the ship. What conclusion can you make? A. They are the same depth B. Water at Point A is twice as deep as that at Point B C. Water at Point B is twice as deep as that at Point A D. Water at Point B is half as deep as that at Point A