Final answer:
A convergent boundary is where tectonic plates move towards each other, often leading to subduction and the formation of geological features such as mountain ranges and ocean trenches.
Step-by-step explanation:
The phrase that best describes a convergent boundary is the region where two tectonic plates are moving towards each other, potentially leading to one plate being forced beneath the other in a process known as subduction. Convergent boundaries can result in the formation of mountain ranges, ocean trenches, and volcanic activity. This type of boundary is characterized by high levels of tectonic activity, including frequent earthquakes.