Final answer:
In high level design, Unified Modeling Language (UML) and Entity Relationship Model (ERM) are options for creating abstract representations of a system. UML visualizes software system designs, while ERM is used for database models. Modeling simplifies the real system by focusing on crucial details for examination.
Step-by-step explanation:
Some options used for high level design are Unified Modeling Language and Entity Relationship Model (ERM). The Unified Modeling Language (UML) is a standardized general-purpose modeling language in the field of software engineering that is used to visualize the design of a system. ERM, on the other hand, is typically used to model databases and shows the system's entities and their relationships. When it comes to high level design, this phase involves selecting a design concept. Designs are evaluated against certain constraints and criteria, and the top choices are further detailed and prototyped. Modeling in this context serves as an abstraction of the real system, simplifying it and focusing on essential details critical for understanding and analysis rather than mirroring every intricate detail of the real system.
Modeling does not aim to be more interesting or to add more details than are in the real system; instead, it simplifies the real system to make it easier to examine, which aligns with option 'a'. In summary, a model in high level design provides a simplified, abstract representation of the design to facilitate better understanding and analysis.