An engineer asks an agent to "add comprehensive tests to this legacy codebase," which has 300 modules, almost no tests, and poorly documented dependencies. Which decomposition approach is most effective?

Answer: A — Map structure and coverage, find high-impact areas, then build a prioritized plan that adapts as you go

Open-ended tasks call for dynamic decomposition: map the structure first, identify high-impact areas, then create a prioritized plan that adapts as dependencies are discovered. Alphabetical order (b) ignores impact, a fixed up-front list (c) can't respond to what's discovered, and a single pass (d) dilutes attention across the whole codebase.