问题如下：
Based on table below, which of the following trends show that PZ has economies of scale?
选项：
A. Increasing gross profit
B. net sales that are increasing with cost of sales
C. Gross profit margins that are increasing with net
sales
解释：
C is correct.
考点：Income Statement Modeling: Revenue
解析：C是正确的。规模经济是指平均成本随着销售量的增加而减少。PZ的毛利润率随着销售额的增长而增长这为规模经济提供了证据。
