During which design activity in software engineering is a suitable data structure for an application typically selected?

Introduction / Context:
Software design is often divided into several related activities, including architectural design, data design, interface design, and procedural design. Each activity focuses on a different aspect of the system. Choosing appropriate data structures for an application is essential for performance and maintainability, and it naturally belongs to one of these design activities. This question asks you to identify which design phase is primarily responsible for selecting suitable data structures.

Given Data / Assumptions:

• A structured software engineering process is being followed, with distinct design activities.
• Data structures include in memory structures such as lists, trees, and graphs, as well as database schemas.
• Architectural design deals with overall system decomposition into subsystems and modules.
• Interface design deals with user interfaces or external system interfaces.

Concept / Approach:
Data design is the activity in which designers identify and specify the data objects that the system will handle and choose appropriate data structures and storage mechanisms to represent them. This includes designing record structures, relationships between entities, and database schemas, as well as selecting in memory collections or data structures that will be used by algorithms. Architectural design, in contrast, focuses on components and their relationships at a high level, while procedural design focuses on algorithmic logic within modules. Interface design is concerned with how users and other systems interact with the software. Therefore, when the question asks where a suitable data structure is chosen, the correct answer is data design.

Step-by-Step Solution:
Step 1: List the main design activities: architectural design, data design, interface design, and procedural design. Step 2: Associate architectural design with high level system organisation and module structure. Step 3: Associate interface design with user interfaces, screens, and external system connections. Step 4: Associate procedural design with detailed algorithms and control flow within modules. Step 5: Recognise that data design is responsible for choosing data structures and data representations, and select option c.

Verification / Alternative check:
Software engineering textbooks typically present data design as a specific phase where designers transform the information domain model into data structures that can be implemented in code or databases. Examples include converting entity relationship diagrams into relational schemas and choosing appropriate indexing strategies. These tasks clearly involve selecting data structures and therefore belong to data design rather than to procedural or interface design.

Why Other Options Are Wrong:
Option a, procedural design, focuses on algorithmic details and step by step logic within modules, which may use chosen data structures but does not primarily select them. Option b, architectural design, addresses system wide structure and component interaction, not low level data representation. Option d, interface design, is about user experience and communication interfaces, not about in memory or persistent data structures.

Common Pitfalls:
A common pitfall is to skip a dedicated data design step and allow data structures to emerge ad hoc during coding, which can result in inconsistent or inefficient representations. Another mistake is to overload architectural diagrams with too many data details, blurring the distinction between architecture and data design. For exam questions, remember that choosing data structures suited to the problem domain is part of data design, as captured by option c.

Final Answer:
A suitable data structure for an application is typically selected during data design, where data structures and database schemas suitable for the application are defined.