I believe the DBQ essay is the correct answer because "DBQ" means "document-based question," and it typically uses primary sources, so it would seem logical for that to be the answer.
The accretionary wedge is like the accretionary prism and the definition of that is : *a mass of sedimentary material scraped off a region of oceanic crust during subduction and piled up at the edge of the overriding plate (source : dictionary)* and the formation is when two plates crash and one slides under the other one I believe and sand ad sediment go into the little open space between them that give you a wedge. Hope I helped.