What do you say when a passenger asks if they can get a refund and then re - book a ticket at a lower fare？

What do you say when a passenger asks if they can get a refund and then re - book a ticket at a lower fare？
A.Sure， go ahead， no problem.
B.Let me check the refund policy and also if the lower - fare ticket is still available. There may be some risks and fees involved.
C.That's a stupid idea.
D.You can't do that.
正确答案：B
试题解析：乘客提出先退票再以更低价格重新购票的想法时，工作人员要先查看退票政策以及低价票是否还有，同时告知可能存在的风险和费用。