问题
单项选择题
All of the following are factors that can cause shifts in the demand curve for a resource EXCEPT:（）
A. an increase in the supply of the resource.
B. an increase in the resource's productivity.
C. a decrease in the prices of other resources.
答案
参考答案：A
解析：
There is no reason to believe that an increased supply will cause a shift in the demand curve. There is no indication to whether a supplier will reduce the price to reflect the change in supply.