What document allows individuals to express their medical care preferences when they are unable to make those decisions themselves?

The correct choice is advanced directives, which are legal documents that allow individuals to outline their preferences for medical care in situations where they are unable to communicate or make decisions for themselves. Advanced directives typically include instructions on the type of medical interventions one wishes to receive or decline, as well as nominating a health care agent who can make decisions on their behalf if they are incapacitated.

Advanced directives are critical in ensuring that a person's wishes regarding their medical treatment are known and respected, particularly during emergencies or serious health situations. They provide guidance to healthcare providers and family members, helping to alleviate confusion and conflict about care preferences during challenging times.

The other options serve different purposes: health insurance policies detail the coverage and benefits of a person's healthcare plan, power of attorney refers to a legal document that allows someone to make decisions on behalf of another person, but not specifically about medical care unless it includes healthcare decision-making authority, and patient consent forms are used to obtain permission for specific medical procedures or treatments but do not express the broader wishes for care in case of incapacity.