A passenger has two pieces of baggage. One is a large suitcase and the other is a small backpack. How should they be checked in？

A passenger has two pieces of baggage. One is a large suitcase and the other is a small backpack. How should they be checked in？
A.Check in the suitcase and let the passenger carry the backpack on the plane.
B.Check in both the suitcase and the backpack.
C.Ask the passenger to put the backpack in the suitcase and then check in.
D.It depends on the passenger's preference and the airline's regulations.
正确答案：D
试题解析：对于乘客的两件行李，一件大行李箱和一件小背包，具体的托运方式取决于乘客个人意愿以及航空公司关于行李尺寸、重量和随身携带规定等。