In requirements engineering, which documents are commonly used to describe and support use cases for a software system?

Introduction / Context:
Use cases describe how users and other actors interact with a software system to achieve specific goals. In requirements engineering, different documents are used together to capture use cases in a clear and testable way. These typically include both graphical diagrams and detailed textual descriptions, plus optional supporting models that help clarify flows and alternatives. This question checks whether you can identify the standard documents used to represent use cases, rather than unrelated diagrams or decorative assets.

Given Data / Assumptions:

• We are documenting requirements for a software system.
• Use cases describe functional requirements in terms of actor system interactions.
• We need both overview diagrams and detailed text.
• Additional diagrams may be used to clarify complex flows.

Concept / Approach:
Use case diagrams are part of the Unified Modeling Language and provide a high level view of actors and their relationships to system use cases. However, these diagrams alone are not enough for implementation and testing. Therefore, teams also write detailed use case narratives or specifications that include preconditions, main success scenarios, alternative flows, and postconditions. To further clarify complex logic, analysts may use activity diagrams, sequence diagrams, or state diagrams that show the flow of control, message exchanges, and transitions. Together, these documents form a consistent, testable description of functional requirements.

Step-by-Step Solution:
Step 1: Recall that a use case is not just a box in a diagram, but a structured description of how an actor interacts with the system. Step 2: Identify the major documents used: use case diagrams for overview, detailed narratives or specifications for step by step behavior, and supporting activity or sequence diagrams for flow details. Step 3: Review the answer choices and find the group that lists these elements together. Step 4: Eliminate options that mention logos, wiring diagrams, voltage charts, or random screenshots, as they do not capture functional requirements. Step 5: Choose the option that clearly mentions use case diagrams, textual use case descriptions, and related behavioral diagrams.

Verification / Alternative check:
Standard requirements engineering practices and many methodology guides describe use case modelling as a combination of diagrams and written narratives. They often provide templates for use case descriptions and examples of supporting sequence or activity diagrams. These references make it clear that meaningful use case documentation goes far beyond decorative images or unrelated hardware drawings and instead focuses on how users achieve goals with the system.

Why Other Options Are Wrong:
Option B is wrong because a company logo conveys no functional requirements or interaction details. Option C, network wiring diagrams, might be useful for infrastructure planning but not for user level use cases. Option D, voltage level charts, relate to hardware design, not software behavior. Option E is incorrect because random screenshots without explanations are not a structured way to capture and analyze use cases.

Common Pitfalls:
A common mistake is to create only use case diagrams without detailed textual descriptions, leaving many ambiguities unresolved. Another pitfall is to document requirements only in plain text without any diagrams, making it harder to see relationships and overlaps. Balancing diagrams with structured narratives and, when necessary, supporting activity or sequence diagrams helps teams build a shared, testable understanding of functional requirements.

Final Answer:
Use cases are typically documented using use case diagrams, detailed use case narratives, and supporting activity or sequence diagrams that together describe actor interactions and system behavior.