Which type of transmission allows signals to be sent simultaneously in both directions?

Full-duplex transmission is the type that allows signals to be sent simultaneously in both directions. This means that both communicating devices can send and receive information at the same time, enhancing communication efficiency and speed. For example, in a full-duplex system like a telephone conversation, both parties can talk and listen without waiting for the other to finish speaking.

In contrast, simplex transmission only allows communication in one direction, meaning that signals can only travel from the sender to the receiver and not vice versa. Half-duplex transmission permits both directions but not at the same time; when one device is sending, the other must wait to send back. Bidirectional is a more general term but does not specifically indicate the simultaneous nature of communication found in full-duplex systems. Thus, the clear distinction of full-duplex allows for seamless communication, making it the correct answer in this context.