Which of the following is true of SITOR ARQ mode:

Correct Answer: Option D — The ship station sends a group of 3 characters, the shore station checks for proper parity. If parity is OK, the shore station indicates readiness for transmission of the next 3 characters.

In SITOR ARQ, the ISS sends a three-character block and waits for a control signal from the IRS. If the IRS confirms the parity is correct, it signals the ISS to proceed with the next block, maintaining a reliable, error-checked communication link between the stations.