What is an advance directive and how does it guide decisions when a patient cannot speak for themselves?

• A. It automatically appoints a guardian and overrides physician judgment.
• B. It expresses preferences for medical treatment (and may appoint a surrogate) and guides decisions to align with patient wishes.
• C. It only applies to end-of-life care and excludes other treatments.
• D. It requires the patient to be hospitalized to be valid.

Answer: (B)