为什么不能选C呢

问题如下：

In the Ricardian trade model, comparative advantage is determined by:

选项：

A.technology. B.the capital-to-labor ratio. C.the level of labor productivity.

解释：

In the Ricardian model, comparative advantage is determined by technology differences between countries. Technology determines output per worker in each industry in each country. Differences in technology between countries cause output per worker in each industry to differ between countries. These ratios determine the pattern of comparative advantage.

中文解析：

在李嘉图模型中，比较优势是由国家间的技术差异决定的。技术决定了每个国家每个行业每个工人的产出。各国之间的技术差异导致每个行业的人均产出在各国之间存在差异。这些比率决定了比较优势的格局。