Final answer:
The correct system used in a clinic for calling into different rooms to give messages to staff is a Paging system, which is distinct from intercom, voicemail, and video conferencing systems.
Step-by-step explanation:
The system used within a clinic to call into different rooms to give messages to the staff is known as a Paging system. An Intercom system is typically a two-way communication electronic device that is used within a building or small collection of buildings. A Voicemail system is a computer-based system that allows users and subscribers to exchange personal voice messages; to select and deliver voice information; and to process transactions relating to individuals, organizations, products, and services. A Video conferencing system is used for holding meetings with participants in different locations using video technology. However, for specifically calling into different rooms to deliver messages, option C) Paging system is the correct answer.