Marina Exam Reviewer: Clear instructions are issued in writing by Master at night order book, which is the most important reminder that he always wrote?

Marina Exam Reviewer

Clear instructions are issued in writing by Master at night order book, which is the most important reminder that he always wrote? 

A. Call the master in case of doubt 
B. Call him to the bridge when meeting a vessel 
C. Call the Master when you change your course 
D. Call the Master when there is a distress alert


Answer:  A. Call the master in case of doubt