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.