Which of the following are TCP/IP protocols used at the Application layer of the OSI model?

The correct answer highlights the applications specifically defined as part of the Application layer of the TCP/IP protocol suite. In the context of the OSI model, the Application layer is where end-user software and network services operate.

Telnet and FTP are both protocols that serve specific purposes at the Application layer. Telnet is used for remote communication with servers, allowing users to log in and execute commands as if they were physically present at the machine. FTP (File Transfer Protocol) is utilized for transferring files between a client and server across the network, providing the necessary commands to upload and download files effectively.

Options that include IP and TCP are inaccurate in this context because both are transport layer and network layer protocols, respectively. IP (Internet Protocol) operates at the Network layer, responsible for addressing and routing packets across networks, while TCP (Transmission Control Protocol) functions at the Transport layer, ensuring reliable transmission of data between devices.

Therefore, only Telnet and FTP can be classified correctly under the Application layer, confirming that this choice accurately identifies the protocols that are relevant to the context of the question.