What causes the subduction zone when an oceanic plate collides with a continental plate?

1) oceanic plates are more dense than continental plates so the oceanic plate dives under the continental plate
2) when the continental plates collide the force is so great that it causes the surrounding crust to collapse
3) continental plates are more dense than oceanic plates so the continental plate dives under the oceanic plate
4) continental plates are more dense than oceanic plates causing the oceanic plate to push upward

1) because oceanic plates are denser than continental plates causing them to subduction

The reason why i feel that the theory of plate tectonics is correct because scientists have found dinosaur bones of the same species in africa, asia, and in the americas. which means that they must have been together at one point in time. plate tectonics is also how the hawaiian islands were formed. as the plate hawaii is on was moving north west, magma would melt through the sea bottom and hardening. forming into the island chain. plate tectonics also explains the mariana trench. two plates were moving away from each other and made a giant crack in the ocean floor running 2,550 kilometers (1,500 miles)  long.