Chapter 15 Describes a Study in Which Researchers Rotated the Type

Chapter 15 describes a study in which researchers rotated the type of sign placed on supermarket displays of sale-priced Campbell's soups. Sometimes the sign announced "No limit per person." Sometimes the sign stated "Limit of four per person."
And sometimes the sign stated "Limit of twelve per person."
Sales were the greatest when the sign announced:

A) "No limit per person"
B) "Limit of four per person"
C) "Limit of twelve per person"
D) Sales were the same regardless of what sign was placed on the displays.
E) None of the above. In fact, no such study is described in Chapter 15.