According to the PMBOK Guide and the Agile Practice Guide, project life cycles are defined by how they handle requirements, activities, and the delivery of the product.
* Iterative Life Cycle (Choice C): In an iterative life cycle, the project scope is generally determined early, but time and cost estimates are routinely modified as the project team's understanding of the product increases. The deliverable is developed through a series of repeated cycles (iterations) that successively add functionality or refine the product. Crucially, the full deliverable is only completed and considered finished after the final iteration. Each iteration improves the quality or detail of the single deliverable until it meets the final requirements.
* Incremental Life Cycle (Choice A): Unlike iterative, an incremental life cycle delivers a functional portion of the product at the end of each iteration. The deliverable is produced through a series of iterations that each add a complete, usable " increment " to the previous ones.
* Predictive Life Cycle (Choice B): Also known as " Waterfall, " this life cycle is characterized by a linear approach where the scope, time, and cost are determined in the early phases of the life cycle. It does not typically use a series of iterations to produce the deliverable.
* Adaptive Life Cycle (Choice D): This is a combination of iterative and incremental (Agile). It uses iterations to refine the product but also delivers functional increments frequently (usually every 2-4 weeks).
The key distinction for an Iterative approach is that the goal is the correctness of the solution through refinement of a single deliverable, whereas an Incremental approach focuses on speed of delivery by providing small, working pieces of the deliverable over time.