4. How are ocean trenches formed?

Question

Here are somethings I think I can put:
Are any of these correct?
• Ocean trenches are formed when oceanic plate cools and moves to the surface of the ocean
• Ocean trenches are formed when the denser oceanic plate sinks.
• Ocean trenches are formed when molten rock cools and solidifies.
• Ocean trenches are formed when magma accumulates on the ocean floor.

Answer 1

When a continental plate converges with an oceanic plate a subduction zone forms. The heavier oceanic plate subducts beneath the lighter continental plate forming a trench.