Which CSOSS lifecycle stage directly precedes implementation?

• A. Validation.
• B. Impact assessment.
• C. Testing.
• D. Documentation.

Answer: (A)

Validation is the step that confirms the proposed CSOSS change meets all defined requirements and constraints, and that stakeholders agree it solves the intended problem without introducing unacceptable risk. This check ensures feasibility, safety, and compatibility with other systems before any resources are spent on execution. If validation passes, you move forward to implementation; if not, the design is revised. Impact assessment evaluates effects on the system and interfaces, but it isn’t the final check right before implementing. Testing verifies performance and behavior, typically in a controlled environment, and often occurs before or alongside implementation rather than as the last gate. Documentation records decisions and details, and can be prepared in parallel, but does not replace the validation before implementation.