Context: Read the passage and look at the picture.
The Aleutian Trench extends 2,900 kilometers along the floor of the Pacific Ocean between Alaska and Russia. At this deep-sea trench, the Pacific Plate and the North American Plate are moving toward each other. As the two plates collide, the Pacific Plate subducts, or sinks, below the North American Plate, forming the Aleutian Trench. This plate movement also causes large earthquakes along the Aleutian Trench.
Complete the sentence.
The Aleutian Trench formed at a () boundary.
A. convergent
B. divergent
C. transform
From the given choices, choose the correct answer and respond with the letter of that choice.

A