Youareunderwayandpassbyalighthouse.Itslight，whichwaswhitesinceyoufirstsightedit，changestored.Thismeans（）.
A.thelightischaracterizedasalternatelyflashingB.thelighthousehaslostpowerandhasswitchedtoemergencylightingC.itistheidentifyinglightcharacteristicofthelighthouseD.youhaveenteredanareaofshoalwaterorotherhazard
参考答案：
D
