题目内容：
根据短文，回答题：
Which of the following is a bad habit of the executive passengers that frustrates the airlines?
A．They do not book their seats in advance.
B．They do not sit on the seats they are supposed to take.
C．They do not travel on the flight they have booked.
D．They do not pay in advance for the seats they book.
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答案解析：