The bottom of the ocean is part of a tectonic plate or continental shelf, or can be on the breach line between two shelves.
both
yes
The ocean floor is the thinnest part.
The Young Ocean Floor is the part of the mantle showing between the 2 split tectonic plates.
sea floor
Along constructive/divergent plate boundaries. This is where the new ocean floor comes from. This is the youngest part of the ocean floor that is.
Continental Shelf.
reef
the abyssal plain
Mid- ocean ridge is the part of the continuous underwater mountain range that circles earth.
The Marianas trench .
The continental shelf