What happens if an association is not correctly defined between two entities?

When an association is not correctly defined between two entities, no data will be linked between them. Associations in database design establish relationships that allow for navigation and data integrity between different entities. When an association is misconfigured or absent, the system lacks the necessary information to connect the data across those entities, meaning that any related data will not be able to interact or be retrieved together. This can lead to incomplete or disconnected datasets, limiting the application's ability to present unified data views.

The other options do not accurately capture the consequence of incorrectly defining an association. Data duplication typically occurs due to improper data management or logic but is not a direct result of an incorrectly defined association. A misconfigured association generally does not lead to an application crash, as the application may still function but will lack proper data linkage. Lastly, stating that all data will be stored in the primary entity does not reflect the incorrect association's impact; rather, it suggests a misunderstanding of how entities and their relationships operate within the data model.