To grant partner users access to cases and records belonging to users at the same role or below, what sharing option should be enabled?

The correct choice is Partner Super User Access. This option is specifically designed to enhance collaboration among partner users by granting them access to appropriate records, such as cases and other records, that belong to users who are at the same role or possess a lower role within the organization.

Enabling Partner Super User Access facilitates a sharing model that not only improves visibility into necessary records but also helps maintain the security and integrity of the organization's data by ensuring that sensitive information is only shared among users with similar roles. This is particularly important in partner relationships where access to data can help in resolving cases, performing joint activities, or ensuring a seamless customer experience.

Other choices do not specifically address the unique needs of partner users. Group Sharing typically relates to internal sharing rather than a partner-based context. Account-Based Sharing could imply a different approach that may not directly facilitate access to cases across roles effectively. View All Data is a broad permission that provides access to all records without regard for role absence, which may not be ideal for managing specific partner user access in a manner aligned with their responsibilities and needs.