2016高考训练题。阅读理解。
阅读下列短文，从每题所给的四个选项（A、B、C和D）中，选出最佳选项。
Since I started working part-time at a grocery store, I have learned that a customer is more than someone who buys things. To me, a customer is a person whose memory fails entirely once he or she starts to push a shopping cart(车). One of the first things customers forget is how to count. There is no other way to explain how so many people get in their express line, which is clearly marked 15 items(件) or less, with 20, 25 or even a cart load of items.
