A consultant needs to evaluate project management methodologies for a new service deployment on the existing network of a customer. The customer wants to be involved in the end-to-end project…

Three principles is not a recognized standard project management methodology applicable to IT service deployments.

Phased methodology uses sequential, gated phases that limit flexibility once a phase is complete, making late requirement changes costly.

Agile divides work into short iterative sprints, providing frequent deliverables and review checkpoints that keep the customer actively involved throughout the engagement. It explicitly supports changing or reprioritizing requirements between sprints, which directly satisfies the customer's stated need for flexibility. No other listed methodology combines frequent updates with formal mechanisms for mid-project requirement changes.

Waterfall locks requirements at the project start and executes phases linearly, making it unsuitable when the customer needs to change requirements as the project progresses.