In ARQ, what action is taken by the information sending station if the parity check fails?

In Automatic Repeat reQuest (ARQ) systems, when a parity check fails, it indicates that the data received by the receiving station is incorrect due to potential errors that occurred during transmission. As a response to this failure, the information sending station takes the necessary action to ensure the integrity of the communication.

The correct action in this scenario is for the sending station to resend the last block of data that was transmitted prior to the failure. This is because the goal of ARQ is to ensure reliable communication by retransmitting erroneous data until it is received correctly. By resending the last block, the sending station attempts to correct the problem and ensure that the receiving station can successfully process the information.

This mechanism is crucial in communication systems, as it helps maintain data integrity and prevents the loss of important information, which can be particularly critical in maritime communication systems governed by the Global Maritime Distress and Safety System (GMDSS).