Which four icons are standard when building a Data Flow Diagram (DFD)?

Introduction / Context:
A DFD communicates how information moves through a system, what transforms it, and where it rests. To keep diagrams consistent and readable, analysts use four standard icons: data flow, process, external entity (source/destination), and data store.

Given Data / Assumptions:

• Notation aligns with common DFD conventions.
• Terminology: “source/destination” is synonymous with “external entity” or “source/sink.”
• Stores represent persistence; flows are arrows; processes are transformations.

Concept / Approach:
The essential elements are: Flow (arrow), Process (circle/rounded rectangle), Source/Destination (square/rectangle), and Store (open-ended rectangle/parallel lines). Grouping them correctly ensures complete coverage of the DFD vocabulary without redundancy.

Step-by-Step Solution:
1) List the canonical four: Flow, Process, Source/Destination, Store. 2) Compare each option’s wording to include all four distinctly. 3) Select the option that explicitly names Source/Destination (external entities) instead of only “Source.” 4) Confirm no element is missing or duplicated.

Verification / Alternative check:
Standard symbol tables in analysis references enumerate these four icons as the foundation of DFDs.

Why Other Options Are Wrong:
Option A/B/D: Wording omits “Destination” explicitly or repeats terms in a way that is less precise; option C is the most accurate formulation.
Option E: Not applicable since a correct grouping exists.

Common Pitfalls:
Confusing external entities with processes or misusing store symbols for temporary variables; DFDs model data movement/persistence, not code variables.

Final Answer:
Flow, Process, Source/Destination, Store