Two tectonic plates of different densities collide. Which of the following could form at the plate boundary? (Multiple answers)

1. island

2. mid-ocean ridge

3. rift valley

4. trench

5. volcano

Trench and volcano could form at the plate boundary.

When two tectonic plates of different densities collide due to convection currents that are produced by the heat within the asthenosphere, a plate boundary (convergent) is formed. Deep trenches are usually formed where one of the plates slides beneath each other (a process called subduction). Trenches are elongated and often narrow cavity. The plate which is below will move down into the mantle, and there will be release of fluids from the rock which will partially melt the mantle. The molten rock will rise and may erupt violently to produce volcanoes.

Other features that could also form at the plate boundaries apart from trench and volcanoes are submarine mountain ranges and fault lines.

The answer is Trench and Volcano, because when two plates of different densities collide. When an oceanic plate and a continental plate collide.