Super User Permission: In Salesforce, the "Super User" permission allows partner community users in specific roles (such as Partner Managers) to access records owned by or shared with users within their partner account. This is an effective and scalable solution for giving partner manager users access to all case and container records for users at the same distributor.

Why Option B is Correct: Granting Super User permissions is straightforward, scalable, and avoids complex configurations such as ownership-based sharing rules or sharing sets.

Why Others Are Incorrect:

Option A: Ownership-based sharing rules are not ideal because they do not accommodate scalability and flexibility across multiple distributors.

Option C: Sharing sets provide access based on the account relationship, but they are limited in scope compared to the flexibility provided by Super User permissions.

For detailed information on Super User permissions, refer to the Salesforce documentation on Partner Communities: https://help.salesforce.com/