Final answer:
The unit manager's policy that permits clients to decide on attending group therapy upholds the ethical principle of autonomy, allowing patients self-determination in their care.
Step-by-step explanation:
The unit manager's policy on an inpatient psychiatric unit that allows clients to choose whether or not to attend group therapy preserves the ethical principle of autonomy. Autonomy in health care refers to the right of patients to make decisions about their own treatment and interventions. When patients are given the choice to participate in group therapy, their autonomy is respected, as they exercise agency and self-determination in their care.