Waterfall model is the correct choice for initiatives that demand strict regulatory oversight and comprehensive documentation at each step.

The Waterfall model uses a linear, phase gated lifecycle with clear stages such as requirements, design, implementation, testing, and maintenance. Each phase produces formal artifacts and requires approvals before moving forward which provides strong traceability and auditability. That formal structure and emphasis on documentation and sign offs align with regulatory requirements and compliance processes.

Spiral model is iterative and risk driven and it focuses on repeated cycles of prototyping and risk assessment. It can include documentation but it does not enforce the same rigid phase gated artifacts and formal approvals that regulators often require which makes it less suitable than the Waterfall approach for strict oversight.

DevOps emphasizes continuous integration, delivery, automation, and close collaboration between development and operations. It prioritizes rapid delivery and feedback which can reduce the emphasis on heavy phase by phase documentation and formal handoffs that many regulatory regimes expect.

Agile values working software and responding to change over comprehensive documentation. Agile methods are intentionally adaptive and lightweight on prescribed artifacts which makes them less appropriate when strict regulatory oversight demands extensive, predefined documentation and formal approvals.

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