Which of the following protocols operates at the Transport Layer of the TCP/IP model and is connectionless?

UDP (User Datagram Protocol) is a connectionless protocol that operates at the Transport Layer of the TCP/IP model. Unlike TCP, which establishes a connection and ensures reliable data transmission with error-checking mechanisms, UDP sends datagrams without establishing a connection and does not guarantee delivery, making it faster but less reliable. It is often used for applications like video streaming or online gaming where speed is more critical than reliability. Option A (TCP) is incorrect because TCP is connection-oriented, meaning it establishes a reliable connection before data is transmitted. Option C (ICMP) is incorrect because ICMP operates at the Network Layer and is used for error messaging and network diagnostics, not data transmission. Option D (FTP) is incorrect because FTP is an application-layer protocol used for file transfer and operates over TCP, not at the transport layer. Option E (HTTP) is incorrect because HTTP is an application-layer protocol for web communication, not a transport-layer protocol.