To identify duplicate Leads in Salesforce, a duplicate job using a Matching Rule is an effective approach.
Duplicate Jobs leverage pre-defined or custom matching criteria to identify records that may be duplicates, which can then be reviewed and cleaned up by marketing reps.
* Matching Rules and Duplicate Jobs: Matching Rules define how duplicate records are identified based on specific field criteria. A duplicate job uses these rules to scan records and generate a report of potential duplicates.
* Supporting Data Quality: This process is efficient for identifying duplicates on a large scale, which can then be reviewed and merged as necessary by marketing reps.
Option A (formula field) and Option B (validation rule) are not designed for detecting duplicates. For more information, refer to the Salesforce Duplicate Management documentation.