In the waterfall model, software development can be managed if the developers are limited to go back only one stage to rework. If this limitation is not imposed mainly on a large project with several team members, then any developer can be working on any phase at any time, and the required rework might be accomplished several times. Answer: B is incorrect. The spiral model is a software development process combining elements of both design and prototyping-in- stages, in an effort to combine advantages of top-down and bottom-up concepts. The basic principles of the spiral model are as follows: The focus is on risk assessment and minimizing project risks by breaking a project into smaller segments and providing more ease-of- change during the development process, as well as providing the opportunity to evaluate risks and weigh consideration of project continuation throughout the life cycle. Each cycle involves a progression through the same sequence of steps, for each portion of the product and for each of its levels of elaboration, from an overall concept-of-operation document down to the coding of each individual program. Each trip around the spiral traverses the following four basic quadrants: Determine objectives, alternatives, and constraints of the iteration. Evaluate alternatives, and identify and resolve risks. Develop and verify deliverables from the iteration. Plan the next iteration.

Begin each cycle with an identification of stakeholders and their win conditions, and end each cycle with review and commitment. Answer: D is incorrect. The Prototyping model is a systems development method (SDM). In this model, a prototype is created, tested, and then reworked as necessary until an adequate prototype is finally achieved from which the complete system or product can now be developed. Answer: C is incorrect. Rapid Application Development (RAD) refers to a type of software development methodology that uses minimal planning in favor of rapid prototyping.