Question

What ocean floor feature is formed when two continental plates spread apart?

continental shelves
Deep sea trenches
Seamounts
mid-ocean ridges

Answer 1

Some ocean trenches are formed by subduction between a plate carrying continental crust and a plate carrying oceanic crust.

Answer 2

Answer is Mid Ocean Ridges
Reason
Where plates diverge (spread apart) from each other, molten magma flows upward between the plates, forming mid-ocean ridges, underwater volcanoes, hydrothermal vents, and new ocean floor crust.