The best way to test the MF-HF SITOR (NBDP) system is to:

The correct answer is to initiate an FEC call to demonstrate that the transmitter and antenna are working. This method is appropriate because an FEC (Forward Error Correction) call allows for continuous transmission of data that includes error-checking mechanisms. By starting an FEC call, you can assess the system's capability to send and receive messages effectively, which directly tests the functionality of the MF-HF SITOR (NBDP) equipment.

FEC calls are useful in determining how well the system handles data integrity, ensuring that the transmissions are not only being sent but also received accurately. This is critical in maritime communication, where equipment reliability and clarity of messages are paramount for safety.

The other methods, while they may demonstrate some aspects of functionality, do not comprehensively test the system in the same way as an FEC call. For instance, initiating an ARQ (Automatic Repeat reQuest) call involves an interactive exchange, which might not fully demonstrate the hardware capabilities if there are issues with the transmission or reception. Making a radiotelephone call does not test the data communication capability of the SITOR system, and an ARQ call focusing solely on the automatic exchange of answerbacks does not test the system's ability to handle error correction during continuous data transmission