What type of diagram shows the logical flow of data through a system?

A Data Flow Diagram (DFD) is specifically designed to illustrate the logical flow of data within a system. It visually represents how data moves between processes, data stores, and external entities. The primary purpose of a DFD is to provide insight into how information is processed and transferred, highlighting the interactions and relationships among various components of a system.

In a DFD, data is depicted through arrows that indicate the direction of flow, while processes are represented by circles or ovals, and data stores by open rectangles. This makes it easy to understand the system at a high level without getting bogged down in implementation details. Its focus on data flow distinguishes it from other diagrams, emphasizing relationships over procedural aspects.

Other choices do not serve the purpose of illustrating logical data flow. Control Unit Diagrams and Control Structure Maps, for example, are more about the control structures and flow of control rather than data. A Data Validation Chart focuses on the rules and criteria for validating data entries and does not provide a comprehensive view of how data flows through a system. Thus, the Data Flow Diagram stands out as the correct choice for representing the flow of data logically and clearly.