Question

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

Answer 1

Trenches and Volcanoes

Answer 2

I don't know if this question is missing some multiple choice options that go along with it, but...

One plate will subduct (go under the other plate), creating a trench or subduction zone. The other plate goes over the subducted plate, creating raised ground. This is how mountains and volcanoes are made.