In a study, shoppers who shopped in a grocery store without a shopping list and bought only items that were on sale for half price or less spent far more money on a comparable number of items than did shoppers in the same store who used a list and bought no sale items. Which one of the following, if true, most helps to explain the apparent paradox in the study's results?
A: The grocery store in the study carries many expensive items that few other grocery stores carry.
B: The shoppers who did not use lists bought many unnecessary items.
C: Usually, only the most expensive items go on sale in grocery stores.
D: Only the shoppers who used a list used a shopping cart.
Choose A, B, C or D as your solution.
C