The E-R model is expressed in terms of: (i) Entities (ii) Relationships among…

Concept

An Entity-Relationship model describes a domain through entity sets, the relationships that associate those entity sets, and attributes that record properties of entities or relationships.

These three construct families answer three different modeling questions: what exists, how the modeled objects are connected, and what descriptive data is stored about them.

Application

In the stem, (i) supplies the modeled objects, (ii) supplies their associations, and (iii) supplies their descriptive properties. Together, (i), (ii), and (iii) cover the E-R model vocabulary named by the definition.

Contrast

• The combination (i) and (iii) describes objects and their properties but omits the association construct.

• The combination (ii) and (iii) describes associations and properties but omits the object sets that participate in those associations.

• None of the above would apply only if every listed combination failed to cover the required construct families; one listed combination does cover them.

Therefore, the correct combination is (i), (ii), and (iii).