You see a vessel displaying three lights in a vertical line.The highest and lowest lights

You see a vessel displaying three lights in a vertical line.The highest and lowest lights are red and the middle light is white.She is also showing a white light at the stern，which is lower than the forward light.It could be a ().

A.Survey vessel

B.Vessel not under command

C.Vessel aground

D.Pilot vessel with port side to you

请帮忙给出正确答案和分析，谢谢！