a trench is forming new crust is forming oceanic crust is subducting a continental plate is subducting
I gave my students this multiple choice question: Sea-floor spreading occurs at divergent boundaries. Which statement best identifies the geologic process taking place at the point where sea-floor spreading occurs?

Only one answer is correct among these 4 choices:
- a trench is forming
- new crust is forming
- oceanic crust is subducting
- a continental plate is subducting

Could you tell me which one is correct?

new crust is forming