参考答案

正确答案：D
解析：从第二段第五句"Errors in prices are eliminated, or done away with", 就可以断定[A]是计算机的优点；根据第二段第七句"UPC gives an itemized receipt to the customer with all the items, prices, and totals", 则又可以肯定[B]是计 computerized system will probably save as much as 45 percent of the checkout clerk's time" ,则可以肯定[C]也是计算机的优点。故[D]是最好的选择，它全面地概括了计算机的优点。