Why do the tectonic plates of ocean plates subduct under land mass plates?

Question

a
Ocean plates move slower than land plates, so land plates move above them
b
Ocean plates are denser than land plates, so they sink under the land plates when the two plates converge
c
Land mass plates are made of porous materials, which absorb the water in the oceanic plates
d
Ocean plates are made of metals, not rocks, so they move lower due to gravity

Answer 1

b
Ocean plates are denser than land plates, so they sink under the land plates when the two plates converge.