Which statements explain what happens at deep-ocean trenches? check all that apply
crust is formed
mountains are formed
seafloor spreading occurs.
crust becomes molten rock.
denser plates slide under lighter plates

C, D, E

Explanation:

At a convergent (destructive) plate boundary. The denser oceanic tectonic plate is moving towards a less dense continental plate. Convection currents in the mantle move the plates together. The continental plate is thicker and higher. At the boundary between the two plates, the oceanic plate starts to slide under the lighter continental plate. The dramatic gap in height between the two plates is the oceanic trench.