In ARQ, when the information sending station (ISS) receives a signal that the parity check failed what happens?

Correct Answer: Option A — The last block will be resent.

When the Information Receiving Station detects a parity error in an ARQ block, it sends a Repeat Request (RQ) signal. Upon receiving this signal, the Information Sending Station (ISS) is required to retransmit the last block of data to ensure the message is received correctly.