Final answer:
The slab-pull theory of plate movement is based on the weight of the subducting crust, pulling plates apart in subduction zones.
Explanation:
Slab-pull theory of plate movement relies on the weight of the subducting crust. It suggests that plates are pulled apart by descending slabs in subduction zones. This concept involves the gravitational force pulling the cold subducting plate down into the mantle at a subduction zone.
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