Which statement is generally correct regarding the maintenance requirements for ships under GMDSS（）.

A.While the ship is at sea，there must be available at all times a supply of electrical energy sufficient to operate the radio installations and to charge any batteries used as part of a reserve source of energy
B.Both the VHF and MF/HF installations must be simultaneously supplied
C.A means of ensuring a continuous supply of electrical power must be provided to all GMDSS equipment that could be affected by an interruption in power
D.If a UPS or equivalent is used to supply power to the ship's GPS receiver or other source of positional information，a means must be provided to ensure the continuous supply of the information in the event of a failure to the ship's main or emergency source of power

A.Locating signals are transmitted by survival craft VHF transceivers
B.Locating signals are transmitted by SARTs
C.Locating signals are intended to facilitate the finding of a distressed vessel or its survivors
D.Locating signals are not transmitted by autoalarm generators

A.Each compulsory vessel must carry at least two licensed GMDSS Radio Operators at all times while at sea
B.Each compulsory vessel must carry at least two licensed Radio Operators at all times while at sea and may elect to carry a GMDSS Radio Maintainer as well
C.Communications involving safety of life at sea do not have to be logged as long as the compulsory vessel was not involved in such communications
D.While at sea，adjustments to，and the maintaining of，GMDSS equipment may be performed by the GMDSS Radio operator as long as the work is supervised by an onboard licensed GMDSS Radio Maintainer