Final answer:
The four layers of the TCP/IP protocol stack are application, TCP, IP, and hardware.
Step-by-step explanation:
The correct answer is a. application, TCP, IP, and hardware.
In the TCP/IP model, which is the protocol suite used for communication over the internet, the protocol stack consists of four layers: application, transport (TCP), network (IP), and network interface (hardware). Each layer has its own specific functions and protocols.
The application layer is responsible for providing services to the end-user, such as email, web browsing, or file transfer. The transport layer (TCP) ensures reliable data transmission between hosts. The network layer (IP) handles the addressing and routing of packets over the network. Finally, the network interface layer (hardware) deals with the physical connection and data transmission on the local network.