Rebecca Decides to Buy a Dress That Hillary Has for Sale;

Rebecca decides to buy a dress that Hillary has for sale; they agree on a price of $20. Which of the following best describes who gains and who loses from the transaction?

A) If the dress originally costs more than $20, Rebecca gains and Hillary loses.
B) If the dress originally costs less than $20, Hillary gains and Rebecca loses.
C) Both parties expect to gain from this transaction.
D) If Hillary gains from the transaction, Rebecca must lose an equal amount.