Oceans Are About Four Times as Deep as Mountains Are

Oceans are about four times as deep as mountains are high. At the bottom of the ocean are

A) huge towering mountains, deep valleys, and deep ocean trenches near the continental borders.
B) thick oceanic crust at the ocean ridges that gradually thins as it nears the deep ocean trenches.
C) towering plutonic mountains created from volcanoes and fissure eruptions at the oceanic trench areas.
D) all of the above