Which of the following is NOT one of the three types of plate boundaries?

The three main types of plate boundaries are divergent, convergent, and transform. A divergent boundary occurs when two tectonic plates move apart from each other, typically leading to the formation of new oceanic crust. A convergent boundary forms when two plates collide, often resulting in one plate being forced beneath the other, a process known as subduction. A transform boundary, on the other hand, occurs when two plates slide past each other horizontally.

Subduction describes a specific process that occurs at convergent boundaries where one plate is pushed under another. While subduction is a significant geological phenomenon associated with convergent plate boundaries, it is not categorized as a type of plate boundary itself. Therefore, it does not fit with the other three types, highlighting why it is identified correctly as the option that does not belong in the list of plate boundary types.