What did later oceanic studies reveal?

Correct answer: The ocean floor has ridges trenches and other features

The direct answer is option B: the ocean floor has ridges, trenches and other features. Earlier ideas sometimes treated the ocean floor as broadly flat or poorly known, but later oceanographic studies used soundings, sonar and mapping to reveal varied relief beneath the water. The ocean floor contains mid-oceanic ridges, deep-sea trenches, plains, volcanic features and other structures. Option A, “the ocean floor is always empty,” is false because it contains many physical landforms. Option B is correct because it accurately describes this varied underwater relief. Option C, “the ocean floor is only air,” is impossible: the ocean floor is the solid bottom beneath the water, made of rock and sediments. Option D, “the ocean floor has no relief,” is also false because relief means differences in height and depth, and these differences are clearly present. These discoveries supported later explanations such as seafloor spreading and plate tectonics. The exam cue is: ocean floor is not flat; remember ridges, trenches and plains. Do not confuse “under the ocean” with “without landforms.”