单项选择题船舶离港之前,所有的吊杆必须纵向收放好。()
A. Before leaving the harbour, all derricks must be stowed.
B. After leaving the harbour, all derricks must be stowed fore and aft.
C. Before leaving the harbour, all derricks must be stowed fore and aft.
D. Before leaving the harbour, all heavy derricks must be stowed fore and aft.