The correct answer is - A) The region is bound by many oceanic trenches.
The Ring of Fire, roughly marking the borders of the Pacific plate with the other plates with which it is in contact, is well known for its geologic activity with the volcanoes and earthquakes, but also it is a place where there's lot of oceanic trenches.
The oceanic trenches appear only on places where an oceanic plate is subducting bellow a continental plate, thus they are a nice evidence of the type of boundary between the plates.
The trenches in this part are numerous, with the Mariana Trench being the best known because it is the deepest place on Earth, than the Tonga Trench, Bougainville Trench, Java Trench, Aleutian Trench, Peru-Chile Trench, and many others.