Multiple Access Protocol for Channel Access Control

CSMA/CD and CSMA/CA are the two multiple access protocols used for channel access control.

CSMA/CD

CSMA/CD stands for Carrier Sense Multiple Access/Collision Detection. In this protocol, every device connected to the network listens to the transmission medium before sending data. If the medium is free, the device begins transmitting data. If two devices transmit data at the same time, a collision occurs, and they stop transmitting and wait for a random amount of time before trying again.

This protocol is used in Ethernet networks, where devices share a common transmission medium like a coaxial cable or a hub.

CSMA/CA

CSMA/CA stands for Carrier Sense Multiple Access/Collision Avoidance. In this protocol, a device listens to the medium before transmitting data. If the medium is free, it sends a short request to transmit (RTS) frame to the receiver. The receiver responds with a clear to send (CTS) frame, indicating that it is ready to receive data. The sender then transmits the data, and the receiver sends an acknowledgement (ACK) frame to confirm that it received the data correctly.

This protocol is used in wireless networks, where the transmission medium is shared among multiple devices, and collisions are more likely to occur due to interference and distance limitations.

Both (a) and (b)

Both CSMA/CD and CSMA/CA are multiple access protocols used for channel access control, with CSMA/CD used in Ethernet networks and CSMA/CA used in wireless networks.

Therefore, the correct answer is option C, Both (a) and (b).