Final answer:
The nurse's accountability in the context of the CNO practice standard for a therapeutic nurse-client relationship is primarily about maintaining professional boundaries to ensure objective and ethical care.
Step-by-step explanation:
According to the CNO (College of Nurses of Ontario) practice standard for a therapeutic nurse-client relationship, the statement that best describes the nurse's accountability is b. maintaining boundaries. This is essential in a therapeutic relationship as it ensures that the nurse remains within the professional scope and does not allow personal relationships to interfere with the objective, compassionate, and respectful care that is mandated by the nursing profession. It involves understanding the distinction between professional and personal relationships, avoiding situations where there could be a conflict of interest, and maintaining the focus on the patient's welfare.