What type of boundary is formed when two tectonic plates collide and one is forced below the other?

When two tectonic plates collide and one plate is forced below the other, this phenomenon is characteristic of convergent boundaries. At these boundaries, the denser oceanic plate typically subducts beneath a lighter continental plate. This process not only leads to the formation of geological features such as mountain ranges and deep ocean trenches, but it also induces significant seismic activity due to the stress and friction that occur at the interface of the colliding plates.

Divergent boundaries, in contrast, occur when tectonic plates move apart from each other, leading to the formation of new crust, typically seen at mid-ocean ridges. Transform boundaries involve plates sliding past each other horizontally, which can also be associated with earthquakes but do not involve subduction. Fault boundaries are a more general term that can encompass various types of boundaries where fractures occur, but they do not specifically denote the subduction process described in the question. Thus, the clear and defining characteristic of convergent boundaries makes it the correct answer in this context.