How can you know the price of the item another person bought without violating other people’s privacy？

How can you know the price of the item another person bought without violating other people’s privacy？
A.Say that you want buy one yourself and ask whether it is expensive.
B.Ask the price directly.
C.Ask the person whether he/she can tell you the price
D.Ask the discount directly.
正确答案：Say that you want buy one yourself and ask whether it is expensive.