Network Interface Port

C

The only time that CSMA/CD (carrier sense medium access with collision detection) is ever needed is when the medium is shared by all devices. In this situation, devices can never send and receive at the same time; they must operate in half-duplex mode. The bitrate is irrelevant.

The statement "A network interface port has collision detection and carrier sensing enabled on a shared twisted pair network" implies that the network interface port is operating in a half-duplex mode. In half-duplex mode, devices on the network can either transmit or receive data at any given time, but not both simultaneously.

Collision detection is a technique used by Ethernet networks to detect and handle collisions that occur when two devices attempt to transmit data at the same time. Carrier sensing, on the other hand, is a mechanism used by network devices to detect the presence of a carrier signal on the network.

Shared twisted pair networks typically use Ethernet technology, which operates at either 10 Mb/s or 100 Mb/s. However, the speed of the network cannot be determined solely from the information given in the statement. Additionally, the fact that the network interface port has collision detection and carrier sensing enabled does not necessarily mean that it is a switch port, as these features are also present on other network devices such as routers, bridges, and network interface cards (NICs) in PCs.

Therefore, the correct answer to the question is C. This is an Ethernet port operating at half duplex.