A manager returned from the U.

Full Detailed in Depth Explanation:

For temporary assignments across legal employers (e.g., U.S. to U.K. Subsidiary), Oracle HCM Cloud provides the Global Temporary Assignment feature.

Option D ("Initiate the End Global Temporary Assignment action and specify a return date. The global temporary assignment is terminated and the assignments in the source legal employer are reinstated automatically on the return date") is correct. When a manager returns from a temporary assignment, the HR representative uses the "End Global Temporary Assignment" action, specifying the return date. This automatically terminates the temporary assignment and reinstates the original assignments in the source legal employer (U.K. Subsidiary), as per the "Using Global Human Resources" guide.

Option A (Descriptive Flexfield) is a custom workaround, not a standard process.

Option B is incorrect; entering a date alone doesn’t trigger reinstatement.

Option C (new assignment) bypasses the temporary assignment framework.