Final answer:
The physician of record must sign off on the progress notes written by the chief resident in Mrs. Smith's chart, as this individual holds the legal responsibility for the patient's care.
Step-by-step explanation:
In the context of medical records and charting, the physician of record is typically responsible for signing off on progress notes made by residents and other members of the healthcare team. The physician of record is the doctor who is ultimately in charge of the patient's care and is legally responsible for overseeing the patient's treatment plan. In the scenario where the chief resident has written progress notes for Mrs. Smith, it is the physician of record who must review and sign off on these notes to ensure continuity of care, compliance with hospital and legal requirements, and the accuracy of the medical record.