Which of the following describes a competent adult's ability to appoint someone to make medical decisions on their behalf?

The ability of a competent adult to appoint someone to make medical decisions on their behalf is best described as a Healthcare Proxy. A Healthcare Proxy is a legal document that allows an individual to designate another person, known as the proxy, to make healthcare decisions for them if they become unable to do so due to illness or incapacity. This designation specifically addresses medical decisions and can encompass a wide range of healthcare options, ensuring that the appointed individual can advocate for the patient’s wishes in medical situations.

While other terms may be related to healthcare decisions, they do not specifically focus on the appointment of an individual to act on behalf of someone else in the context of healthcare. For instance, a Healthcare Directive often refers broadly to a document that provides instructions regarding an individual’s healthcare preferences, but it does not specifically appoint someone to make decisions. A Living Will outlines a person's wishes concerning end-of-life care, thus providing guidance to healthcare providers, but it does not delegate decision-making authority to another person. Similarly, a Durable Power of Attorney grants authority to another person for a range of actions, which may include financial matters but does not exclusively pertain to healthcare decisions unless it specifies medical decisions.