In entity–relationship (ER) modeling, evaluate the following definition and choose whether it is correct or not.\n\n“An ID-dependent entity is an entity whose identifier is a composite identifier where no portion of the composite identifier is an identifier of another entity.”

Introduction / Context:
ID-dependent (also called weak) entities are a foundational topic in data modeling. The question asks whether an ID-dependent entity's key excludes any parent identifier. Understanding this distinction helps you model one-to-many ownership, enforce referential integrity, and create meaningful primary keys for intersection tables and weak entities.

Given Data / Assumptions:

• We are using standard ER terminology: entity types, attributes, identifiers (keys), relationships.
• “ID-dependent entity” means an entity whose existence and identification depend on a parent entity.
• Composite identifier means a primary key made of two or more attributes.

Concept / Approach:
By definition, an ID-dependent entity has an identifier that includes the identifier of another (owner/parent) entity. Typical examples are OrderLine depending on Order, or Dependent depending on Employee. The key of the weak/ID-dependent entity “borrows” the parent’s key (fully or a unique part of it) and adds its own partial key (like line_no) to form a composite identifier.

Step-by-Step Solution:
State the standard rule: a weak or ID-dependent entity’s primary key includes the parent’s primary key.Compare with the statement: it claims that no portion of the composite identifier is an identifier of another entity.This directly contradicts the rule, because the composite key must contain the parent’s key.Therefore, the definition given is incorrect.

Verification / Alternative check:
Consider Order(order_id) and OrderLine(order_id, line_no). OrderLine is ID-dependent; its PK contains order_id, which is part of the parent’s identifier. This falsifies the given statement.

Why Other Options Are Wrong:
“Valid statement” contradicts the standard definition. “Sometimes valid only in weak-entity diagrams” is self-contradictory because weak entities are exactly where parent keys are included. “Ambiguous” is unnecessary—this is a clear definitional point. “Not applicable” is irrelevant; the concept is core to ER modeling.

Common Pitfalls:
Confusing composite identifiers in general with ID-dependence; assuming “composite” implies total independence from any parent. Also, mixing up identifying vs. non-identifying relationships.

Final Answer:
Invalid statement