Oceanic Lithosphere Subducts Sinks into the Asthenosphere

Oceanic lithosphere subducts sinks into the asthenosphere. because_______ .

A) the convection of the mantle pulls the lithosphere into the asthenosphere
B) old oceanic lithosphere is more dense that the asthenosphere
C) the upwelling magma at divergent boundaries pushes the lithospheric plate into the asthenosphere
D) the pressure from two plates colliding forces one plate into the asthenosphere