What can a living will specify?

A living will is a legal document that outlines a person's preferences regarding medical treatment in situations where they may be unable to communicate their wishes due to incapacitation. It specifically addresses wishes concerning life-sustaining treatment, such as the use of ventilators, resuscitation efforts, or artificial nutrition and hydration.

By clearly stipulating what types of medical interventions should or should not be pursued in critical situations, a living will ensures that a person's healthcare preferences are respected, even when they cannot speak for themselves. This makes option C the correct choice, as it directly reflects the primary function of a living will.

The other options, while related to healthcare decisions, do not accurately describe the scope of a living will. Payment instructions for healthcare refer to financial aspects of medical care rather than treatment preferences. The designation of a healthcare power of attorney involves appointing someone to make medical decisions on behalf of an individual but is not something a living will dictates. Similarly, arrangements for transportation to hospitals focus on logistics rather than medical treatment preferences, which is outside the purview of a living will.