Final answer:
The obligation to maintain confidentiality in a hospital applies to doctors, nurses, and patients.
Step-by-step explanation:
The obligation to maintain confidentiality in a hospital applies to all of the above, which includes doctors, nurses, and patients. This obligation is rooted in ethical principles and legal requirements such as the Health Insurance Portability and Accountability Act (HIPAA). Confidentiality is crucial in protecting patients' privacy and fostering trust in the healthcare system.