Final answer:
A Durable Power of Attorney for Health Care is a written document that appoints a person as a proxy responsible for making medical decisions on behalf of a patient.
Step-by-step explanation:
The written document that names a person as a proxy responsible for making medical decisions on behalf of a patient who is unable to do so for themselves is called a Durable Power of Attorney for Health Care. This document allows the appointed proxy, also known as a health care agent, to make decisions and advocate for the patient's medical treatment preferences.
A Durable Power of Attorney for Health Care can be coupled with a living will, which is a legal document that specifies the medical interventions a person wants or does not want in certain situations, especially at the end of life.
The other options listed in the question are not specifically related to appointing a proxy for medical decisions.