Provide your best answer for the following question. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The question is: The Andes Mountains in South America formed when an oceanic plate shifted beneath a continental plate. Which other landforms are usually associated with this type of plate boundary?
ocean trenches
Volcanic arc, subduction zone.