Final answer:
Stepwise refinement in life-cycle models is indeed iterative and incremental. It involves breaking down tasks and making gradual improvements with each iteration of prototyping, testing, and evaluation.
Step-by-step explanation:
The concept of stepwise refinement in a life-cycle model is often associated with a process that is both iterative and incremental. Stepwise refinement means breaking down a large task into smaller, more manageable steps, improving the design or software in a gradual fashion. It is true that stepwise refinement underlying life-cycle model is iterative and incremental. An incremental design refers to making improvements to an existing product or process in pieces and could also imply enhancing an existing product or process. The design process is iterative as it often undergoes cycles of prototyping, testing, evaluating, and refining.
Moreover, the iterative nature of this process is further emphasized by the need to continuously develop and improve upon existing skills and designs, which is common in many life-cycle models such as the spiral design process. This contrasts with a purely sequential process where steps follow each other without reconsideration of previous stages.