An app builder is loading data into Salesforce.

The correct answers are C. Unique and D. External ID.

The legacy ID should be stored in a custom field marked as an External ID because Salesforce uses External ID fields to identify records from an outside system and to support update/upsert operations during future data loads. The field should also be marked Unique so each legacy system ID maps to only one Salesforce Account record and avoids duplicate-match problems during upsert. Salesforce documentation defines External ID fields as fields that contain record identifiers from outside Salesforce and can be used to update or upsert records.

A. Required is not necessary for the upsert-matching requirement.

B. Encrypted/Text encrypted is not appropriate because encrypted fields are not used for this legacy-ID matching purpose.

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