In what scenario is Transmission Control Protocol (TCP) preferred over UDP?

Transmission Control Protocol (TCP) is preferred in scenarios where guaranteed delivery of messages is essential. This is because TCP is a connection-oriented protocol that establishes a connection between the sender and receiver before transmitting data. It ensures that all packets are received in the correct sequence, and if any packets are lost during transmission, TCP automatically retransmits them. This reliability makes TCP ideal for applications where data integrity and complete transmission are critical, such as file transfers, web page loading, and email communications.

In contrast, other scenarios highlighted in the options involve priorities like speed (where UDP, a connectionless protocol, might be favored) or real-time requirements (which often align with the lower latency of UDP). However, when the need for reliable communication is paramount, TCP remains the preferred protocol due to its built-in mechanisms for error detection, retransmission, and ordered delivery.