Repetition of a DSC Distress call is normally automatic if not acknowledged after a delay of:

Correct Answer: Option C — 3.5 - 4.5 minutes

ITU-R M.541 standards specify that if a DSC distress alert is not acknowledged by a coast station or ship, the equipment must automatically repeat the transmission. This cycle occurs at intervals between 3.5 and 4.5 minutes to ensure the alert is eventually received without requiring constant operator intervention.