When creating a use case diagram which of the following relationships may a business analyst (BA) use?

Question

Options

• AExtend, include
• BOutput, input
• CExtend, enhance
• DAllow, prevent

• A
  91% (21)
• B
  4% (1)
• C
  4% (1)

Explanation

Option A is correct because use case diagrams in UML formally define two relationship types between use cases: extend (a use case conditionally adds behavior to a base use case) and include (a use case mandatorily incorporates another use case's behavior). These are the standard BA tools for modeling optional vs. required functionality in system interactions.

Why the distractors fail:

• B (Output, input): These describe data flow, which belongs to data flow diagrams (DFDs), not use case diagrams.
• C (Extend, enhance): "Enhance" is not a UML relationship - it's a plausible-sounding fabrication; the real pairing is extend/include.
• D (Allow, prevent): These are not UML concepts at all and have no place in use case modeling.

Memory tip: Think "E.I., E.I., O" - Extend, Include are the only two (like the farm song). Or remember: you include what's always needed, and extend what's optional - like including bread in a sandwich but only extending it with mayo if requested.

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