A business analyst (BA) is working on a payment system (PS) implementation. A set of systems which should interact with a new system has been identified. The business analyst defined that a user with

Vertical prototyping creates a working model of a single specific feature or technology layer to validate feasibility, and does not address the definition of inter-system communication protocols.

Interface analysis examines the inputs and outputs at system boundaries but is applied to elicit interface requirements, not to define the overarching communications protocol technique for use case modeling.

Concept modelling defines domain entities and their relationships at a business level and does not address how systems technically communicate or exchange data.

System analysis involves examining the components, interfaces, and interactions of a system to understand how each part operates and communicates. When a BA is building a Use Case diagram for a payment system that interfaces with external systems, system analysis provides the structured approach to identify and define the communication protocols governing those interactions. This technique covers the scope of inter-system data exchange and behavioral expectations necessary to complete the diagram accurately.