Here's why:

* Convergent Plate Boundaries: When two tectonic plates collide, they can either push against each other (continental-continental collision) or one plate can slide beneath the other (subduction zone). This collision and pressure cause the land to buckle, fold, and uplift, forming mountains.

* Divergent Plate Boundaries: These boundaries occur when tectonic plates move apart. This process typically leads to the formation of mid-ocean ridges and rift valleys, not mountains.

Examples of mountain ranges formed at convergent boundaries:

* Himalayas: Formed by the collision of the Indian and Eurasian plates.

* Andes Mountains: Formed by the subduction of the Nazca plate beneath the South American plate.

* Rocky Mountains: Formed by complex interactions of tectonic plates, including subduction and continental collision.