Which statement best describes the top-down design approach to problem solving?

• A. Break the solution into high-level modules first, then refine each module into smaller components.
• B. Start with detailed code and then generalize.
• C. Design everything at once before coding.
• D. Avoid breaking the problem into subproblems.

Answer: (A)

Top-down design starts by outlining the entire solution at a high level and identifying the major modules and their interfaces first. You define the big pieces and how they interact, then progressively break each piece into smaller submodules and details. This approach keeps the overall structure in view and helps you manage complexity by hiding implementation details behind clear interfaces.

That’s why it’s the best fit: starting with high-level modules gives you a coherent architecture, makes it easier to reason about data flow and dependencies, and allows you to test and verify the system step by step as you refine each module. It also supports parallel work, since different developers can implement different modules once their interfaces are settled.

The other approaches don’t align with this idea. Jumping straight into detailed code before the overall structure is defined is more bottom-up or iterative in a way that can lose sight of how parts fit together. Designing everything at once tries to capture all details upfront, which can be rigid and hard to change. Avoiding subproblems defeats the whole purpose of modular design, which is to break a complex problem into manageable pieces.