A synthetic key is generated by Qlik when two or more tables have more than one field in common. In this scenario, both the Orders and Shipments tables share OrderID and LineNo, which correctly define the relationship at the order-line level. The standard and best practice to resolve this type of synthetic key is to create a single composite key. This is achieved by creating a new field in both tables that concatenates the common fields (e.g., OrderID & '-' & LineNo). This new composite key then serves as the single, unambiguous link between the tables, resolving the synthetic key while maintaining the correct data granularity and associations.

A. Removing LineNo from Shipments breaks the logical link at the order-line level, causing data integrity issues. The AutoNumber function is not a solution for this type of synthetic key.

B. Removing LineNo from both tables results in a significant loss of critical business information, as the concept of an individual order line is destroyed.

D. While removing the original fields from one table is part of a full implementation, this option describes a specific tactic. The fundamental strategy is the creation of the composite key itself, making option C the more accurate and primary answer.

1. Qlik Sense for Windows Help. In the section on data modeling, the topic of synthetic keys is discussed. It states, "When two or more tables have two or more fields in common, this results in a synthetic key... The solution is to create a custom key that represents the combination of the two keys." This directly endorses the creation of a composite key. (Search for "Synthetic keys" in the official Qlik Sense product documentation).

2. Qlik Continuous Classroom. The "Data Modeling for Qlik Sense" course, specifically the module on "Resolving Data Model Issues," presents the creation of a composite key as the primary and recommended resolution strategy for synthetic keys that arise from a valid multi-field relationship between tables. It demonstrates concatenating the fields to form a new, single key.