Which of the following is NOT a mode of communication?

The correct answer is multi-directional, as it is not recognized as a standard mode of communication in telecommunication terminology.

To understand why, it's essential to define the various recognized modes of communication, such as simplex, half duplex, and full duplex.

• Simplex communication refers to a one-way transmission where data flows in only one direction. An example would be a television broadcast, where signals are sent from the TV station to the receiver without any return communication.

• Half duplex allows for two-way communication but not simultaneously. An example of this mode is a walkie-talkie system, where one party can talk while the other listens, and then they switch roles.

• Full duplex permits simultaneous two-way communication, enabling both parties to send and receive data at the same time. A telephone conversation exemplifies full duplex, as both parties can communicate back and forth without waiting.

In contrast, multi-directional does not correspond to these established categories. While it might imply a form of communication involving multiple directions, it lacks the definitive characteristics and operational mechanics of the recognized modes. Hence, it is not an accepted term in the context of communication modes.