Answer:
It is legitimate to charge different prices to different customers if: the retailer is related to the customer.
Step-by-step explanation:
Differential pricing, where different prices are charged to different customers, can be legitimate in cases where the retailer has a familial or business relationship with the customer. This could include offering discounts or special pricing to family members, employees, business partners, etc. However, the other options mentioned (bartering/flexible pricing, publically-traded company status, one-time occurrence, and price difference less than or equal to ten percent) are not necessarily the sole criteria for determining the legitimacy of charging different prices to different customers.