问题
单项选择题
Holding the quantity of labor constant, output increases as the quantity of capital increases, but at a decreasing rate. This phenomenon is most accurately described as:（）
A. diminishing marginal costs of capital.
B. diminishing marginal returns to labor.
C. diminishing marginal product of capital.
答案
参考答案：C
解析：
The marginal product of capital is the change in output divided by a unit change in capital, holding labor constant. Diminishing marginal product of capital means that at a constant level of labor, output increases as capital is added, but at a decreasing rate.