For GMDSS，when may a compulsory vessel not be allowed to leave port?（）

A. When the vessel is in an overloaded condition
B. When the vessel has arranged for both duplication of equipment AND shore-based maintenance
C. When the vessel has replaced a required piece of GMDSS-related equipment but its performance has not been verified or logged
D. When the vessel is carrying only two licensed GMDSS Radio Operators and is capable of performing all required functio