What do computers on a network use to initiate and break connections?

Transport Control Protocol (TCP) is the correct answer because it is specifically designed to facilitate the establishment, management, and termination of connections between computers on a network. TCP operates at a level in the networking model that ensures reliable transmission of data. It performs this by establishing a connection through a process known as a "three-way handshake", where the initiating device sends a connection request, the receiving device acknowledges this request, and then the connection is established.

Once the data transmission is complete, TCP also provides mechanisms for properly closing the connection, thus ensuring that both devices are aware that the communication has ended. This reliability and orderly approach to managing connections are essential for network communication, particularly for applications that require guaranteed delivery, such as web browsing and file transfers.

The other protocols mentioned serve different purposes within network communication. Internet Protocol (IP) is responsible for addressing and routing packets of data but does not establish connections directly. File Transfer Protocol (FTP) is used to transfer files but relies on TCP for the connection process. Hypertext Transfer Protocol (HTTP) is designed for transferring hypertext (such as web pages) over the internet, but again, it operates on top of TCP, relying on it for connection management.