Which type of communication allows data to be sent in both directions at the same time?

Full duplex communication is the correct answer because it refers to a communication system where data can be transmitted and received simultaneously between two parties. This means that both participants in the communication can send and receive messages at the same time without waiting for the other to finish.

For example, a telephone conversation illustrates full duplex communication, where both speakers can talk and listen simultaneously without interrupting each other. This is essential in many modern communication technologies that require seamless interaction, such as video conferencing and real-time data transfer.

In contrast, half duplex communication allows data to be sent in both directions, but not at the same time. This means that while one party is transmitting data, the other must wait until the transmission is complete before responding. Examples of this include walkie-talkies, where one person has to say "over" before the other can reply.

Simplex communication, on the other hand, only allows data to flow in one direction, meaning that one party can only send information while the other can only receive it, such as a keyboard sending input to a computer.

Serial duplex is not a standard term in communications. Therefore, focusing on the characteristics of full duplex highlights its capability for simultaneous two-way communication, making it the correct choice.