In TCP/IP, what does the 'Transmission Control Protocol' primarily handle?

In TCP/IP, the Transmission Control Protocol (TCP) primarily handles the reliable delivery of data between devices over a network. Its main function is to ensure that data sent from one device reaches another accurately and in the correct order. TCP achieves this through several mechanisms, including error checking, data segmentation, and connection-oriented communication.

When a connection is established between two devices, TCP manages the flow of data by breaking down larger messages into smaller packets and ensuring that they arrive at their destination. If any packets are lost or received out of order, TCP handles retransmission and reordering, providing a reliable communication channel. Thus, TCP's primary role in the TCP/IP suite is to ensure that data is delivered reliably across the internet, making the correct answer focus on how it transfers information between networks effectively.

The other options relate to different aspects of networking. While establishing connections is indeed a part of TCP's functionality, its primary focus is on managing data transmission reliably. Routing packets is a function performed by other protocols within the TCP/IP suite, particularly the Internet Protocol (IP), which is responsible for directing packets to their intended destinations. Storing data securely is handled by other protocols and technologies, such as encryption protocols, which are distinct from TCP's primary functions.