What does a system process model define?

A system process model primarily defines the sequential flow of control among programs within a system. This means that it outlines how different processes interact with each other and the order in which they are executed. By representing these processes and their interdependencies, the model provides a clear understanding of the overall workflow, which can help in identifying potential inefficiencies, bottlenecks, or integration points.

Understanding the sequence of operations is crucial for system design, as it aids in planning how data is processed and how components will function together to achieve desired outcomes. This sequential perspective not only enhances clarity but also serves as a foundation for rigorous testing and validation, ensuring that system requirements are met effectively.

Regarding the other options, they address different aspects of system architecture or design. The parallel execution of multiple programs pertains to concurrent processing, which is less about the flow of control. Hierarchical organization focuses on the structural arrangement of components rather than their execution flow. Lastly, user interface design is concerned with how users interact with the software, which is separate from the process model itself.