Option C: Update the PrimaryId__c field definition to mark it as an External Id.
Correct Answer.
Marking PrimaryId__c as an External ID allows data loading tools to match records based on this field.
This facilitates upserting data and ensures that the CSV data correctly maps to existing records.
A trigger is unnecessary when External IDs can be used for mapping.
Option B: Create a before save flow to correctly map the records.
Incorrect.
A flow adds unnecessary complexity; External IDs suffice.
Option D: Upload the CSV into a custom object related to Candidate__c.
Unnecessary.
This does not streamline the process and complicates data management.
Conclusion:
The developer should update the PrimaryId__c field to mark it as an External ID, which is Option C.
Reference:
Upserting Records with External IDs
Option A: Create a before Insert trigger to correctly map the records.
Incorrect.