Final answer:
The 'System Smart List' for identifying 'Possible Duplicates' defaults to using the 'Email Address' attribute to find duplicate records, leveraging its uniqueness to individuals.
Step-by-step explanation:
The 'System Smart List' titled "Possible Duplicates" typically uses the Duplicate Fields special filter to identify potential duplicate records within a database or a Customer Relationship Management (CRM) system. By default, this smart list primarily relies on the Email Address attribute to locate duplicates. This is because the email address is unique to each individual and is considered one of the most reliable identifiers for detecting multiple records that pertain to the same person.