Question

Where does subduction occur?

A. at hot spots
B. at mid-ocean ridges
C. at continental shelves
D. at deep ocean trenches

Answer 1

Answer: C. at continental shelves

Answer 2

Well, the answer I always learned was "where two places collide"

So I think your best bet is answer C.

This is cause they often collide and grind against each other, which btw is what causes earthquakes if you didn't know.