Explanation: Inmarsat terminals provide specific hexadecimal error codes to inform users about connection issues. When a terminal fails to establish a connection to the Mobile Packet Data Service (MPDS) network because it has not successfully registered, the system displays "00F0h" or "00F1h." Registration is a fundamental step in satellite communication, signifying that the terminal has been authenticated and recognized by the network, allowing it to access services. Without successful registration, no data connection can be established. Options A, B, and C describe different, incorrect, or non-standard error codes and formats for this particular failure. "ECM 0071" or "77F0h/77F1h" are not the correct indicators for a terminal not being registered to the Inmarsat MPDS network. Option B also uses "ECM" and the reason "failure to transmit" is a consequence, but "not registered" is the specific initial cause indicated by "00F0h/00F1h".