Computer Science for IGCSE & O level - Data Transmission (Section 1 - No. 19)

In an ARQ system, what does a 'negative acknowledgement' (NAK) indicate?

The receiver has successfully received the data.

The receiver is ready to send data.

The receiver has detected an error in the received data.

The sender should stop sending data.

A NAK (negative acknowledgement) tells the sender that an error occurred, and the data should be retransmitted.