At the check - in counter， what information do you first ask a passenger？

At the check - in counter， what information do you first ask a passenger？
A.Their favorite movie.
B.Their flight number or booking reference.
C.Their pet's name.
D.Their shoe size.
正确答案：B
试题解析：在办理登机手续时，首先需要询问乘客的是航班号或预订参考号，这样才能快速准确地找到乘客的预订信息，进行后续的办理流程。