Final answer:
Modeling the requirements and allocating them to subsystems should be done in the Analysis stage, which is crucial for system development and precedes design refinement through prototyping and testing.
Step-by-step explanation:
The question is asking about the stage of development in which modeling the requirements and allocating requirements to subsystems activities should take place. The correct answer is D. Analysis. This stage is crucial for breaking down the requirements comprehensively and deciding how different parts of the system will handle the specified requirements. It sets the foundation for the detailed design where processes such as prototyping, testing, and refinement come into play.
During the Analysis stage, different subsystems are often identified, and requirements are allocated accordingly. This systemic approach helps to clarify how each part of the system contributes to the overall functionality. After analysis, the team can proceed to develop prototypes and refine the design through iterative testing and evaluation, improving the design to meet the established criteria and constraints more effectively.