Which documentation method is specifically used to represent entity behavior and functions?

Model-based documentation is the correct choice because it effectively captures and represents the behavior and functionalities of entities in a structured and visual manner. This method typically involves creating models, such as UML diagrams or other types of graphical representations, which clearly illustrate how entities interact and operate within a system.

By utilizing visual elements, model-based documentation allows stakeholders to more intuitively understand the relationships and behaviors of the components being documented. This clarity is often necessary for analysis, design, and communication among team members, facilitating a shared understanding of the system's functions.

Other methods like natural language documentation or textual descriptions may provide some insight into entity behavior but often lack the structured approach that model-based documentation uses to visually represent these interactions. Visual documentation can overlap with model-based techniques, but it is often less formal and may not fully encapsulate the functional aspects, which are critical for understanding entity behavior. Therefore, model-based documentation stands out as the preferred choice for clearly articulating entity behavior and functions.