Universal Containers has an order system that uses an Order Number to identify an order for customers and service agents. Order records will be imported into Salesforce. How should the Order Number…

Direct Lookup is not a field type or attribute for defining an identifier field; it refers to a type of relationship field in Salesforce.

Defining a field as an External ID allows Salesforce to recognize this field as containing unique identifiers from an external system, which is crucial for data integration and matching during imports or updates. Marking it as Unique further ensures that no duplicate Order Numbers will exist within Salesforce, preserving data integrity from the source system.

Lookup is a type of relationship field used to link two records together, not for defining a unique identifier from an external system for the primary record itself.

Indirect Lookup is a relationship field type specifically used for external objects, which is not applicable here as the order records are being imported *into* Salesforce, not linked to an external object.