What frequencies are used for receiving HF MSI

A、HF MSI is transmitted on a primary frequency of 518KHZ and on a secondary frequency of 490KHZ.
B、HF MSI is transmitted on 8414.5KHZ plus one other (undesignated) HF frequency.
C、HF MSI is transmitted on the third ITU channel in each HF band (2,4,6,8,12,16 and 22MHZ)
D、HF MSI is transmitted on certain dedicated frequencies.