9-21B6 B
 If the vessel is experiencing atmospheric interference with NAVTEX broadcasts, especially in the tropics, the GMDSS operator should:
A. Select one of the 6 HF MSI frequencies and set-up the transceiver in ARQ TELEX mode.
B. Select one of the 8 HF MSI frequencies and set-up the transceiver in FEC TELEX mode.
C. Select one of the 6 MF MSI frequencies and set-up the transceiver in FEC TELEX mode.
D. Select the MF MSI frequency dedicated to tropical MSI and set-up the transceiver in FEC TELEX mode.
