Question

1. i think that one plate sinks into the mantle and is destroyed at plate boundaries.

Explanation:

The question is about plate tectonics, specifically where one tectonic plate sinks into the mantle and is destroyed. In plate tectonics, this occurs at convergent plate boundaries (specifically subduction zones, which are a type of convergent boundary). So the missing term should be "convergent" (or more specifically "subduction" but in the context of plate boundaries, "convergent" is the boundary type where subduction happens).

Answer:

convergent