问题
单项选择题
A vessel transferring provisions or cargo at sea shall display during the day（）.
A.two black balls in a vertical line
B.three black balls in a vertical line
C.three shapes in a vertical line； the highest and lowest shall be red balls and the middle a white diamond
D.three black shapes in a vertical line； the highest and lowest shall be balls and the middle one a diamond
答案
参考答案：D