Which statement correctly describes simplex, half-duplex, and full-duplex communication?

• A. Half-duplex is one-way; simplex is two-way but not simultaneous; full-duplex is simultaneous one-way.
• B. Simplex is one-way; half-duplex is two-way but not simultaneous; full-duplex is two-way simultaneously.
• C. Full-duplex is one-way; simplex is two-way simultaneously; half-duplex is two-way but not simultaneous.
• D. Simplex is two-way; half-duplex is one-way; full-duplex is fully mute.

Answer: (B)

Understanding how data can flow helps you see why this description is correct: simplex, half-duplex, and full-duplex differ by both direction and simultaneity of transmission.

Simplex means one-way only — signals travel in a single direction with no return path on the same channel. Think of a broadcast like a radio or TV signal where receivers can listen, but there’s no built-in mechanism for those receivers to send messages back on that channel.

Half-duplex allows two-way communication, but not at the same time. When one side transmits, the other must listen; then they switch roles. A common example is a walkie-talkie, where users take turns speaking.

Full-duplex enables two-way communication to happen simultaneously. Both sides can transmit and receive at the same time, which you see in a telephone call or in certain networking links that use paired channels or techniques to separate the two directions.

So the statement that correctly captures these relationships is: simplex is one-way; half-duplex is two-way but not simultaneous; full-duplex is two-way simultaneously. The other choices mix up one-way versus two-way or simultaneous versus non-simultaneous and don’t match these definitions.