VACUUM in Delta Lake removes unreferenced files older than a retention period (default 7 days, but configurable, e.g., 30 days).
It ensures that the transaction log remains consistent and ACID properties are maintained.
OPTIMIZE with V-Order or Z-Order improves file organization and query performance, but it does not remove unused files.
Deleting files manually from OneLake would break the transaction log consistency.
Correct answer: C. Run the VACUUM command.
Reference: VACUUM in Delta Lake