What defines the cardinality and foreign key relationships between object types?

• A. Object Type defines cardinality.
• B. Interface defines cardinality.
• C. Link Types define relationships between object types, specifying cardinality (one-to-one, one-to-many, many-to-many) and which properties serve as foreign keys.
• D. Properties define foreign keys.

Answer: (C)

The way object types relate to each other, including how many records from one side can connect to records on the other side and which fields link them, is defined by Link Types. They serve as the relationship blueprint between object types, explicitly specifying the cardinality (one-to-one, one-to-many, many-to-many) and which properties act as foreign keys.

Think of two object types, like Customer and Order. A Link Type can encode that a single customer can have many orders (one-to-many) and that the Order records hold a customer identifier as a foreign key. If you need a many-to-many relationship, the Link Type expresses that as well, potentially using a junction-like structure. This is what ties the data together and enforces how the records relate in a scalable way.

Object types themselves define the shape of data, not how they relate. Interfaces describe capabilities or contracts, not the specifics of how entities connect. Properties are attributes of an object type and may include identifiers, but the overall relationship pattern and foreign-key wiring come from Link Types.