（单选题）
When testing a Class A EPIRB you will know the EPIRB is working properly if you hear on 99.5 Mhz FM or any vacant frequency on a nearby AM radio（）.
Aa distinctive signal
Bthe Morse Code signal for SOS
Ca computerized voice announcement of Mayday
Dyour vessel's International Radio Call Sign
正确答案
答案解析
略
