in january there was a large drop in the number of new houses sold,because interest rates for mortgage were falling and many consumers were waiting to see how low 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,best explains the sharp rise in the average price of new house?

A,sales of higher-priced house were unaffected by the sales drop because their purchasers have fewer constraints limiting the total amount they pay.

正确答案是A，但是我不明白，A中并没有说higher-priced house提价，只说它不受interest rates影响，更没说明提交很sharp。

为什么要选这个呢？