Which document gives instruction for withholding life-sustaining procedures?

The correct answer is the living will. A living will is a specific type of advance directive that outlines an individual's preferences regarding medical treatment in scenarios where they are unable to communicate their wishes. This document explicitly states the person's wishes concerning life-sustaining procedures, indicating whether they would like to receive such interventions or not in the event of a terminal condition or incapacitation.

This clear expression of intent is crucial for healthcare providers and family members, ensuring that a person's desires regarding the prolongation of life are respected even when they cannot voice them. The living will serves as a guide during critical medical situations, providing clarity on the patient's values and choices regarding end-of-life care.

In contrast, the other documents mentioned serve different purposes and do not specifically relate to withholding life-sustaining treatment. A standard power of attorney allows another person to make financial or legal decisions on someone else's behalf, while a durable power of attorney provides broader powers that are effective even during a period of incapacitation, but may not specifically address healthcare wishes. A healthcare proxy designates someone to make medical decisions for an individual when they are unable to do so, but it does not itself outline the individual's preferences regarding specific medical treatments.