The correct answer is: A. TCP/IP
The TCP/IP model is a conceptual model that describes how data is communicated over a network. It is a four-layer model, with each layer providing a specific set of services to the layers above it. The layers are:
- Application layer: This layer provides services to the applications that are using the network. For example, the HTTP protocol is used by web browsers to communicate with web servers.
- Transport layer: This layer provides reliable, ordered, and error-checked delivery of data between applications. The TCP protocol is used for this purpose.
- Internet layer: This layer provides routing and addressing services. The IP protocol is used for this purpose.
- Network access layer: This layer provides access to the physical network. For example, the Ethernet protocol is used for this purpose.
The TCP/IP model is a widely used standard for networking. It is used by the Internet, as well as by many other networks.
The other options are incorrect because they are not models of networking. HTTP is a protocol that is used to transfer hypertext data over the Internet. SMTP is a protocol that is used to send email. UTP is a type of cable that is used to connect devices to a network.