Studying ridges and trenches together shows which feature of the ocean floor?

Correct answer: Dynamic processes like creation and destruction

The direct answer is option A: studying ridges and trenches together shows that the ocean floor is dynamic, with processes of creation and destruction. At many mid-ocean ridges, magma rises and cools to form new oceanic crust. At deep ocean trenches, old oceanic crust may sink beneath another plate at a subduction zone. Thus one feature is associated with building crust and the other with consuming or recycling crust. Option A is correct because it links both landforms to active plate processes. Option B is wrong because the ocean floor is not completely still. Option C is wrong because sediment deposition alone cannot explain ridges and trenches. Option D is wrong because water colour has no role in this structural interpretation. The reasoning is: ridge formation plus trench subduction equals a changing ocean floor. Memory cue: ridge builds; trench takes down.