Question

Which of the following statement about a Data Flow Diagram (DFD) is true?

• A. A DFD represents the physical implementation of a system.
• B. A DFD shows how data moves through a system, including processes, data stores, and external entities.
• C. A DFD is used to write sources code directly.
• D. A DFD ignores the flow of data and focuses only on user interface design.

Hint:

Remember: A DFD shows What a system does (Data flow), whereas a Flowchart shows How a system does it (Sequence and logic).

Answer 1

The Correct Option is B

Concept:
A Data Flow Diagram (DFD) is a graphical representation of the "flow" of data through an information system. It is a logical modeling tool that focuses on what happens to the data, rather than how it is physically stored or how the interface looks.

Step 1: Four Basic Elements of a DFD.
Every standard DFD uses four symbols:
• External Entities (Squares): Sources or destinations of data outside the system boundary.
• Processes (Circles/Bubbles): Actions that transform inputs into outputs.
• Data Stores (Open Rectangles): Where data sits when not in use (e.g., a file or database).
• Data Flows (Arrows): The movement of data between the other elements.

Step 2: Logical vs. Physical.
A DFD is primarily a logical tool. It describes the functional requirements of the system. While "Physical DFDs" do exist to describe specific hardware, the core definition of a DFD (and its primary use) is to map out the path of information.

Step 3: Conclusion.
Option (B) perfectly summarizes the standard definition of a DFD. It does not contain control logic (like loops or if-statements) which distinguishes it from a Flowchart. It strictly shows the movement and storage of data.