Which of the following provides instruction about life-sustaining medical treatment for a patient who has a terminal disease?

A health care proxy is a legal document that designates an individual to make medical decisions on behalf of a patient who is unable to do so. While it empowers someone to act according to the patient's wishes, it does not itself provide specific instructions about life-sustaining treatments, unlike a living will which directly details those preferences.

Active euthanasia involves the intentional act of ending a person's life to relieve suffering, typically in cases of terminal illness. This choice represents a decision to end life rather than provide instructions for ongoing medical care. Thus, it does not align with the concept of sustaining life through medical treatment as outlined in a living will.

Organ donation refers to the process of giving one's organs after death for transplant purposes. While it is an important medical decision, it does not pertain to the instruction regarding life-sustaining treatments for a patient with a terminal disease, which is the focus of a living will.