Final answer:
The Agile model is best suited for a system with multiple subsets of functionality used in different areas.
Step-by-step explanation:
The best model suited for a system that includes several subsets of functionality used in more than one area of the system is the Agile model.
The Agile model emphasizes collaboration, flexibility, and iterative development. It allows for continuous feedback and adaptation to changing requirements, making it ideal for systems that require multiple subsets of functionality across different areas.