Question at position 45 A "one-to-many" relationship in an ERD indicates thatOne entity instance is associated with exactly one instance of another entityOne instance of an entity is associated with zero instances of another entityOne instance of an entity is associated with multiple instances of another entityMany instances of an entity are associated with many instances of another entity

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BlackTom AI · Accepted Answer

Question restatement:
Question at position 45 A "one-to-many" relationship in an ERD indicates that

Option list:
1) One entity instance is associated with exactly one instance of another entity
2) One instance of an entity is associated with zero instances of another entity
3) One instance of an entity is associated with multiple instances of another entity
4) Many instances of an entity are associated with many instances of another entity

Option 1 analysis:
- This describes a one-to-one relationship, where a single instance of the first entity pairs with exactly one instance of the second entity. It does not convey multiplicity beyond a single pairing.
- Misconception addressed: confusing "exactly one" with the broader concept of one-to-many; the key feature of one-to-one is a 1:1 mapping, not 1:N.

Option 2 analysis:
- This depicts a scenario where the first entity has no related instances of the second entity, which corresponds to zero cardinality in one direction. It does not describe a productive or typical relational link like one-to-many.
- Misconception addressed: absence of related entities is not how one-to-many is defined; the relationship exists and involves multiple related instances when it occurs.

Option 3 analysis:
- Here, a single instance of the first entity is linked to multiple instances of the second entity. That multiplicity is the hallmark of a one-to-many relationship: one side can be associated with many on the other side, but each related instance on the many side is connected to only one instance on the one side.
- This aligns with the standard ERD notation for one-to-many relationships and contrasts with one-to-one and many-to-many patterns.

Option 4 analysis:
- This describes a many-to-many relationship, where many instances of the first entity relate to many instances of the second entity. It does not fit the one-to-many pattern, which restricts the relationship on the "one" side.
- Misconception addressed: confusing many-to-many with one-to-many, which involves a single instance on the "one" side corresponding to multiple on the other side, but not reciprocal many-to-many.

Putting it together:
- Evaluating the multiplicity descriptions across options shows that Option 3 captures the essence of a one-to-many relationship: a single instance on the one side relates to multiple instances on the many side, while preserving a singular link from the many side back to the one side. The other options describe one-to-one, zero-or-none, or many-to-many scenarios, which do not fit the definition of one-to-many.

In summary, option 3 matches the standard definition of a one-to-many relationship in an ERD, whereas options 1, 2, and 4 describe other relationship types or edge cases that do not reflect one-to-many semantics.

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