问题
单项选择题
At a fixed level of capital, output increases as the quantity of labor increases, but at a decreasing rate. This phenomenon is an example of:（）
A. law of diminishing costs to labor.
B. law of diminishing returns to capital.
C. law of diminishing returns to labor.
答案
参考答案：C
解析：
The law of diminishing returns states that at some point, as more and more of a resource (e. g. , labor) is devoted to a production process, holding the quantity of other inputs constant, the output increases, but at a decreasing rate.