单选题 Holiday receipts—the total sales recorded in the fourth quarter of the year—determine the economic success or failure of many retail businesses. Camco, a retailer selling just one camera model, is an excellent example. Camco"s holiday receipts, on average, account for a third of its yearly total receipts and about half of its yearly profits.
If the statements above are true, which of the following must also be true about Camco on the basis of them?

A、 Its fixed expenses per camera sold are higher during the fourth quarter than for any of the other three quarters
B、 It makes more profit during the first and third quarters combined than during the fourth quarter
C、 Its per-camera retail price is lower, on average, during the fourth quarter than during any one of the first three quarters
D、 It makes less profit, on average, for a given dollar amount of sales during the first three quarters combined than during the fourth quarter
E、 The per-camera price it pays to wholesalers is higher, on average, during the fourth quarter than during any of the other three quarters

【正确答案】 D

【答案解析】[解析] 本题作为归纳题型，属于对比推理类型。假定Camco年销售收入为X元，利润为Y，那么就一定金额的销售数量而言，第四季度的利润率为

，而其他三个季度为

，而