I showed up to the interview dressed to the nines, post double shot latte, and mentally prepped only to be ushered to a hallway lined with chairs and a dozen other potential applicants already waiting their turn. I knew I needed something to make me stand out if I had any chance of securing the job.
Answer 1: At plate boundaries where sea-floor spreading occurs, magma wells up to fill the space created by the plates that are moving apart. Check out this United States Geologic Survey (USGS) educational animation to see visually how it works:
A trench is due to the convergence of two oceanic plates. One is subducted under the other and forms a deep trench. A mid-ocean ridge is due to sea floor spreading. There, two oceanic plates are being pushed apart due to the formation of new sea floor. This new sea floor creates a large ridge.