Here's why:

* Convergent boundaries are where two tectonic plates collide.

* This collision causes the plates to push against each other, resulting in compressional forces.

* These forces can lead to several geological features:

* Mountain ranges: Like the Himalayas, formed when two continental plates collide.

* Subduction zones: Where one denser plate slides beneath another, often resulting in volcanic activity.

* Earthquakes: Caused by the immense pressure and friction generated by the collision.

While compression is the dominant force, there are other forces at play, such as:

* Tension: This occurs in the overriding plate as it stretches and bends due to the subduction process.

* Shear: This can occur along the boundary where the plates slide past each other.

However, compression is the defining force that shapes the landscape and geological activity at convergent boundaries.