This is consistent with the theory, because same-direction collections are supposed to produce few earthquakes.

This is consistent with the theory, because these plate collisions could be in the same direction. If so, we’d expect few earthquakes.

Plates descend at a shallow angle when they collide in opposite directions. If plates collide in opposite directions, we’d expect many earthquakes. So (C) undermines the proposal by showing that there aren’t many earthquakes in a zone with opposite-direction collisions.

This is consistent with the proposal. The scientists never suggest that there must be more factors in the size of the plane of contact besides the angle of subduction. So if it turns out that the size of the plane of contact is related only to the angle of subduction, this doesn’t undermine the proposal.

This is consistent with the proposal. Plates descending at a steep angle occur when the plates collide in the same direction. When plates collide in the same direction, we expect few earthquakes.