Which four objects are keyed by a Reference Data Set to allow sharing and restricting...

Full Detailed in Depth Explanation:

Reference Data Sets (RDS) in Oracle HCM Cloud control the sharing and restriction of reference data across business units. The four objects keyed by RDS include:

Jobs (A): Shared or restricted by business unit for employment consistency.

Grades (D): Linked to compensation and restricted by RDS.

Location (E): Physical work locations shared or restricted via RDS.

Departments (F): Organizational units managed via RDS for segregation.