Question

A volcano.
The volcano in the image is called Ol Doinyo Lengai. This volcano formed as a result of two plates separating.

Which other type of plate boundary forms volcanoes?

Answer 1

Convergent (subduction) plate boundaries. When one plate is forced beneath another it melts and forms magma that rises to create volcanoes (e.g., the Andes, the Cascades, and the Japanese island arc).

(Transform boundaries generally do not produce volcanoes; hotspots away from plate boundaries also make volcanoes, e.g., Hawaii.)