问题如下：
A company plans to hire additional factory employees. In the short run, marginal returns are most likely to decrease if:
选项：
A. the factory is operating at full capacity.
B. the factory is experiencing a labor shortage.
C. workers are required to multitask and share duties.
解释：
A is correct.
The law of diminishing returns occurs in the short run when additional output falls as more and more labor is added to a fixed amount of capital. When a factory is operating at full capacity, adding additional employees will not increase production because the physical plant is already 100% employed. More labor hours will add to costs without adding to output, thus resulting in diminishing marginal returns.
考点：边际效用递减
劳动力短缺的情况下，增加劳动力是可以增加边际产出的。B选项不入选
分工本身是专业化的表现，也可以增加边际产出。C选项不入选
厂房满负荷运作，表明产量很难增加。但是工人现在增加了，那么边际产量会出现下降。A选项入选。
选项可以解释一下吗，劳动力短缺？
