If a passenger wants to change their reservation from economy class to business class， you might respond with：

If a passenger wants to change their reservation from economy class to business class， you might respond with：
A.Sure， it's free of charge.
B.There will be an additional charge for the upgrade. Are you okay with that？
C.Business class is always full.
D.You can't upgrade your reservation.
正确答案：B
试题解析：升舱通常需要额外付费，明确告知乘客并询问其意愿，符合实际情况和服务规范。