单选题 In January there was a large drop in the number of new houses sold, because interest rates for mortgages were falling and many consumers were waiting to see how low the rates would go. This large sales drop was accompanied by a sharp rise in the average price of new houses sold.
Which of the following, if true, best explains the sharp rise in the average price of new houses?

A、 Sales of higher-priced houses were unaffected by the sales drop because their purchasers have fewer constraints limiting the total amount they pay.
B、 Labor agreements of builders with construction unions are not due to expire until the next January.
C、 The prices of new houses have been rising slowly over the past three years because there is an increasing shortage of housing.
D、 There was a greater amount of moderate-priced housing available for resale by owners during January than in the preceding three months.
E、 (E) Interest rates for home mortgages are expected to rise sharply later in the year if predictions of increased business activity in general prove to be accurate.

【正确答案】 A

【答案解析】[解析] 决定所售新房子平均价格的因素主要看所售高价新房与所售低价新房之间的相对比例或权重。所售新房数目既定，而其中高价新房权重大的所售新房平均价格绝对大于高价新房权重比较小的所售新房平均价格。因此(A)指出高价房销量不变而低价房销量下降时，所售新房中高价房权重增大，所以所售新房价格激增。(A)解释了新房子平均价格的激增，因此(A)正确。