问题如下图：
选项：
A. 
B. 
C. 
解释：
B选项不能理解成net profit margin吗？我算的百分比，比C的gross profit margin大
NO.PZ201512300100000501 Profit margins thare increasing with net sales Gross profit margins thare increasing with net sales C is correct. Economies of scale are a situation in whiaverage costs crease with increasing sales volume. Chrome’s gross margins have been increasing with net sales. Gross margins thincrease with sales levels provi evinof economies of scale, assuming thhigher levels of sales refleincreaseunit sales. Gross margin more rectly reflects the cost of sales thes profit margin. 老师 这题是不是不用算可以直接选？
NO.PZ201512300100000501 B为什么错
请问B为什么不对呢？
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？
