What does it mean when a cannon is described as self-propelled?

A cannon described as self-propelled means that it has the ability to move itself without needing external assistance or power sources, such as towing vehicles or manual labor. This characteristic allows the cannon to relocate independently on the battlefield, enhancing its tactical flexibility and operational capabilities.

Self-propelled cannons typically integrate propulsion systems that allow them to navigate various terrains while simultaneously providing fire support. This feature is particularly advantageous in fast-paced combat situations where mobility is key for both offense and defense. The other options describe scenarios where the cannon either relies on external forces or cannot move independently, which does not align with the definition of a self-propelled system.