What symbol denotes a mandatory constraint on an entity's relationship?Question 2Answera.a circle or 'o'b.an arrow or '<'c.a vertical line or '|'

The symbol that denotes a mandatory constraint on an entity's relationship in the context of Entity-Relationship (ER) diagrams is represented by a vertical line or |.

Explanation

In ER diagrams, relationships between entities can have cardinality constraints that define the number of instances of one entity that can or must be associated with instances of another entity. A mandatory relationship implies that an instance of one entity must be associated with at least one instance of another entity.

• Vertical Line (|): This symbol is used to indicate that the relationship is mandatory for that entity. If an entity has a vertical line in relation to another, it means that for each occurrence of the first entity, there must be at least one related occurrence in the second entity.

• Circle (o): This symbol typically indicates an optional relationship where an entity can exist without a related instance in another entity.

• Arrow (<): This is not a standard notation for indicating mandatory constraints in ER diagrams.

Final Answer

c. a vertical line or '|'