What role does the Transport layer play in the OSI model?

The Transport layer is critical in the OSI model, primarily responsible for ensuring reliable data transmission between end systems. It achieves this through mechanisms that manage error recovery, flow control, and data segmentation. When data is sent over a network, the Transport layer breaks it into smaller packets and ensures that these packets are delivered accurately and in the right order. If any packets are lost or corrupted during transmission, the Transport layer can detect these issues and request retransmission, thus maintaining data integrity.

By providing services such as connection-oriented communication (like TCP) or connectionless communication (like UDP), the Transport layer allows different applications on the same device or across different devices to communicate effectively. This function is essential for applications that require reliable communication, such as web browsing, email, and file transfers, where data accuracy is paramount.

The other roles mentioned in the alternatives do not pertain to the Transport layer. The management of physical connections and signaling is the responsibility of the Physical layer, routing and forwarding of data is handled by the Network layer, and data encryption is typically a function associated with security protocols operating at various layers, rather than a specific function of the Transport layer.