Final answer:
The principle of justice is most relevant to the nurse's concern regarding differing treatments for patients with similar self-mutilation risks. The correct answer is option d.
Step-by-step explanation:
The ethical principle that most clearly applies to the concern raised by the nurse regarding the use of restraints for one patient while another patient receives one-on-one supervision to prevent self-mutilation is the principle of justice.
The principle of justice involves fairness in the distribution of resources and treatment. The nurse questions whether it is ethically appropriate to provide different levels of care to patients who have similar risks and needs. The situation embodies an ethical dilemma in the equitable distribution of resources and attention.
The principle of beneficence, which requires acting in the best interests of the patient. In this context, while beneficence is a contributing factor in deciding the levels of care provision, the emphasis lies on ensuring fair and equal treatment, thus highlighting the importance of justice.