Which feature forms as a result of a tectonic plate boundary that creates an underwater mountain range in the open ocean?

At a divergent plate boundary, tectonic plates move apart and magma rises to create new oceanic crust. This builds a long underwater mountain range called a mid-ocean ridge, so the correct choice is mid-ocean ridge. A trench forms where plates converge, while marshes and abyssal plains are not underwater mountain ranges.

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