Which MAC sublayer function is responsible for controlling the NIC that sends and receives data on the physical medium?

• A. Provides synchronization between source and target nodes.
• B. Adds Layer 2 control information to network protocol data.
• C. Places information in the frame that identifies which network layer protocol is being used for the frame.
• D. Controls the NIC responsible for sending and receiving data on the physical medium.

Answer: (D)

The MAC sublayer is in charge of accessing the physical medium and coordinating the NIC to actually send and receive frames. It sits at the boundary between the data-link layer and the physical layer, managing how frames are placed on the wire and how incoming frames are taken from the wire to the NIC. So the function that best matches “controlling the NIC that sends and receives data on the physical medium” is the MAC’s role itself.

The other descriptions relate to related tasks but not to controlling the NIC. Synchronization is about timing, not specifically NIC control. Adding Layer 2 control information describes framing details like addresses and error checking, which are part of frame construction rather than the NIC control itself. Indicating which network layer protocol a frame carries is about payload identification, not NIC control.