Which of the Following Is a Reason Why Airline Yield

Which of the following is a reason why airline yield management is an effective method to increase revenue?

A) Because airlines have invested heavily in developing computer models that identify optimal pricing strategies in the various market segments.
B) Because airlines have successfully induced customers to reveal their resources and preferences by offering them different versions of the product, such as business class and coach plane tickets.
C) Because a ticket is a contract to transport a specific person, and is not transferable.
D) Because airlines have a monopoly in long-distance carriage.