题目内容
（请给出正确答案）
[单选题]
According to the STCW Convention, when taking watch in port on ships carrying hazardous cargo in bulk, there shall be ready availability on board __（）
A.a qualified officer or officers, and ratings
B.a master and ratings
C.a master and a duly qualified officer
D.a master, a duly qualified officer and ratings when appropriate
答案
A、a qualified officer or officers, and ratings
