Since the Creation of the Hershey Candy Bar Over 100

Since the creation of the Hershey candy bar over 100 years ago,the price of chocolate has fluctuated,but the price of the candy bar has slowly risen.In fact,when the price of chocolate had dramatic price fluctuations over a three-year period,the price of a Hershey's candy bar remained the same.When the price of chocolate was very high,Hershey's was able to maintain its profits by making the bars smaller.Hershey's engaged in:

A) top-down marketing.
B) trading up.
C) bottom-up marketing.
D) downsizing.