What defines Simplex Communication?

Simplex communication is characterized by the ability to send data in only one direction. This means that one party can transmit information while the other party can only receive it, without the capacity to respond or send information back at the same time. This type of communication is commonly found in scenarios such as a television broadcast, where the signal is sent from the station to the viewers without any feedback channel allowing viewers to send data back to the station.

The other options reflect different modes of communication that are not related to simplex. For instance, simultaneous two-way audio transmission refers to duplex communication, where both parties can communicate at the same time. The option about audio being sent in both directions, one at a time, describes half-duplex communication, which allows for communication back and forth but not simultaneously. Lastly, the mention of permitting audio and video transmission interchangeably does not directly correlate to the simplex definition, as simplex communication strictly refers to unidirectional transmission, regardless of the type of media (audio, video, etc.). This reinforces the unique characteristic of simplex as a unidirectional flow of information.