Universal Containers has recently implemented an Experience Cloud site to allow its customers to create...

For Experience Cloud customer users, Sharing Sets are the correct mechanism to provide access to records linked to their own Contact or Account. By creating a sharing set for the Case object, UC can ensure users see only the cases where they are the associated contact—even if the cases were created internally.

Option A (sharing rule) applies to internal users, not Experience users.

Option C (Public Read/Write) violates data security and exposes all customer cases.

Referenced Salesforce Materials:

Service Cloud Consultant Exam Guide – Service Cloud Solution Design Domain.

Salesforce Help: “Grant Record Access to Portal Users with Sharing Sets.”

Salesforce Experience Cloud Implementation Guide – Sharing Set Configuration.