Question

which event causes the formation of trenches in earths crust?
magma rising
mantle emerging
volcanoes erupting
lithosphere colliding

Explanation:

Trenches are formed at convergent - plate boundaries where the denser oceanic lithosphere subducts beneath the less - dense continental or another oceanic lithosphere. Magma rising is related to volcanic activity at mid - ocean ridges or hotspots. Mantle emerging is not a common term for trench formation. Volcanoes erupting are a result of magma reaching the surface, not the cause of trench formation. Lithosphere colliding, specifically oceanic lithosphere subducting under another plate, causes trench formation.

Answer:

lithosphere colliding