Final answer:
Advance directives guide healthcare decisions when a person is incapacitated, allowing individuals to outline their healthcare wishes and appoint a healthcare proxy.
Step-by-step explanation:
The correct statement regarding advance directives is that they guide healthcare decisions in case of incapacitation. Advance directives are not limited to being established by physicians, are not only applicable to elderly patients, and are not automatically in effect for all patients upon admission. Instead, these legal documents are proactive measures that individuals can put into place to outline their healthcare wishes, including decisions about treatments, such as life-extending measures, and appointing a health care proxy to make medical decisions on their behalf if they become unable to do so.