Final answer:
Compression stress occurs when one plate pushes against another, often at convergent boundaries.
Step-by-step explanation:
The type of stress that occurs when one plate pushes against another is compression. Compression stress occurs when forces act to squeeze or shorten an object along its axis. In the context of plate tectonics, compression stress is often associated with convergent boundaries where plates collide, causing one plate to be forced beneath the other in a process known as subduction.
Learn more about Plate tectonics