问题如下：
1. Based on Exhibit 1, which of the following provides the strongest evidence that Chrome displays economies of scale?
选项：
A.Increasing net sales
B.Profit margins that are increasing with net sales
C.Gross profit margins that are increasing with net sales
解释：
C is correct.
Economies of scale are a situation in which average costs decrease with increasing sales volume. Chrome’s gross margins have been increasing with net sales. Gross margins that increase with sales levels provide evidence of economies of scale, assuming that higher levels of sales reflect increased unit sales. Gross margin more directly reflects the cost of sales than does profit margin.
请问下这里的Profit margin指的是NI/ sales么？ 我算了一下这个是下降的，但是答案的说选C的原因是gross 比profit margIn更好？ 老师好像没有讲到过？
