What is the fundamental（基本） concept of the GMDSS?
A. It is intended to automate and improve existing digital selective calling procedures and techniques.
B. It is intended to automate and improve emergency communications in the maritime industry.
C. It is intended to provide more effective but lower cost commercial communications.
D. It is intended to provide compulsory vessels with a collision avoidance system when they are operating in waters that are also occupied by non-compulsory vessels.
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