To restrict access to only Person Accounts for the retail sales team while maintaining a private OWD:

Option A (Correct): Create criteria-based sharing rules. These rules can be defined to share accounts of type PersonAccount with users in the Retail Sales role. This ensures they can only access retail customers (Person Accounts) and not Business Accounts.

Option B: Sharing on AccountContactRelation does not provide direct access to accounts and is irrelevant to this requirement.

Option C: Updating the profile to grant access to the Person Account record type does not align with the private OWD and does not manage access to records individually.