Final answer:
The nurse-manager is demonstrating the controlling function of the management process by addressing a nurse's suspected breach of client confidentiality on social media.
Step-by-step explanation:
When the nurse-manager is addressing a nurse's suspected breach of client confidentiality in a social media posting, she is demonstrating the controlling function of the management process. Controlling, one of the four core functions of management, involves monitoring staff performance and taking corrective action when needed. In this scenario, the nurse-manager is taking steps to correct an action that potentially violates patient privacy and confidentiality, which are fundamental aspects of healthcare practice. This involves investigating the issue, identifying whether a breach has occurred, and implementing measures to prevent future occurrences, thereby aligning with the key activities of the controlling function.