A document which sets forth an individual's preferences for the use of life prolonging measures (tube feeding, ventilator) if they are incapacitated is called a __________.

The correct answer is a living will. A living will is a specific type of advance directive that explicitly outlines an individual's preferences regarding medical treatment, particularly concerning life-prolonging measures, in the event that they become incapacitated and cannot communicate their wishes. It typically addresses situations such as the use of tube feeding or mechanical ventilation, providing clear instructions to healthcare providers and family members about what actions should or should not be taken in those circumstances.

While advance directive can refer to a broader category of documents that express a person's healthcare preferences, the living will focuses specifically on end-of-life decisions and care options. Other options, like medical power of attorney, designate a person to make healthcare decisions on someone’s behalf but do not specify treatment preferences directly. A health care directive may encompass various forms of advance directives, but the living will is the most precise term for the document that details wishes regarding life-sustaining treatments.