Which of the following is not an example of constraints that can limit flexibility in the human resource planning process ？（）

A．Organizational structur

B．Collective bargaining agreement

C．Economic condition

D．Activity resource requirement

下列选项中，属于活动式防火分隔设施的是（）。

A.楼板

B.防火墙

C.防火隔间

D.防火卷帘