Answer:
A trench forms in an underwater subduction zone, often near continental boundaries.
Step-by-step explanation:
Trenches are often found close to continents because of the subduction boundaries in which a plate made of oceanic crust slides underneath a less dense plate made of continental crust. The downward movement of the denser oceanic plate causes the formation of a deep underwater chasm. It is important to note that near divergent oceanic plate boundaries, the separating plates form an underwater ridge, not a trench.