Which layer of the TCP/IP model is equivalent to the Session, Presentation, and Application layers of the OSI model?

The correct answer is the Application layer of the TCP/IP model, as it encompasses the functionalities provided by the Session, Presentation, and Application layers of the OSI model.

In the TCP/IP model, the Application layer is responsible for high-level protocols that enable user-level applications to communicate over a network. This includes providing functionalities such as establishing sessions, data formatting, and user interface specifications. The inclusion of the Session and Presentation functions within the Application layer of TCP/IP allows for a simpler and more streamlined protocol suite that effectively handles all user-service interactions in a single layer.

The distinction between the two models illustrates that while the OSI model separates these functions into three different layers for clarity and organization, the TCP/IP model consolidates them into one comprehensive Application layer for practical application. This reflects the TCP/IP model's focus on real-world networking scenarios, where the exact separation of functions may not be as critical.