In Disciplined Agile, teams are encouraged to be flexible andevolve their life-cyclebased on their context, learning, and needs. As teams gain experience, they may start with one life-cycle model and later transition to another that better suits their situation (e.g., moving from Scrum-based to Lean continuous delivery). This flexibility enables the team to optimize their way of working for continuous improvement.
Options A, B, and C are not correct. The inception phase does not last until the architecture is proven; the transition phase is not necessarily about the amount of functionality built; Agile and Lean life-cycles can include inception and transition phases.
References:
* PMI's Disciplined Agile Senior Scrum Master (DASSM) curriculum materials.
* "Choose Your WoW! A Disciplined Agile Delivery Handbook for Optimizing Your Way of Working (WoW)", PMI.