Explanation: A SART (Search and Rescue Transponder) is an active device designed to be detected by marine radar. When a SART detects a pulse from a searching vessel's 3-cm (X-band) radar, it immediately transmits a series of 12 distinct blips back to the radar. These blips appear as a line of dots on the searching vessel's radar display, indicating the SART's range and bearing, and guiding rescuers to the survival craft. This automatic response is its primary function. A) IFF (Identification Friend or Foe) interrogation systems are military aviation applications and are not used with GMDSS (Global Maritime Distress and Safety System) SARTs. C) VHF-FM Ch-70 is the dedicated Digital Selective Calling (DSC) distress channel. While a survival craft might have a DSC radio, a SART is a radar transponder and does not transmit on or monitor VHF-FM Ch-70. D) This option is almost correct but contains a critical error. SARTs are designed to respond to **3-cm (X-band)** radar signals, not 10-cm (S-band) radar signals. The 3-cm band is more common for marine navigation and provides better resolution for detecting small targets like survival craft.