In general, where on earth are the subduction zones located?

In general, they are on the edges of continents, where you find mountain ranges, regular earthquakes and active volcanoes - Eg: South America and Asia.

Subduction zones are where tectonic plates collide, with a plate plunging beneath the other.
Sometimes these collisions are gradual but often they occur in large movements that can cause concussions.
  As the subduction zones are generally on seabeds, earthquakes can trigger tsunamis in these areas.

Europe may be starting to dive under Africa, creating a new subduction zone and potentially increasing the risk of earthquakes in the western Mediterranean Sea.

Bwould be my guess |-/ 

Ithink the answer to that would be b):