Earlier We Discussed the Concept of Isostasy, Where Lower Density

Earlier we discussed the concept of isostasy, where lower density rocks rise higher than higher density rocks. How is the variation of water depth at spreading centers ridges. controlled by isostasy?

A) Volcanic rocks are lighter than other rocks, and so the abundant volcanic rocks at the ridges are lower density features that produce the seafloor topography.
B) The lithosphere cools as it moves away from the ridge axis by sea floor spreading, and cooler rocks are lower density, so the sea floor gets deeper as the lithosphere gets more dense.
C) Oceanic ridges are sites where the lithosphere is carried into the mantle on one side aka subduction zones., and the volcanoes along these margins produce the ridge by buildup of lower density crust.
D) It has nothing to do with isostasy; the areas are simply high because there are chains of active volcanoes along the ridge crest, producing the topography.