以下关于高致病性禽流感受威胁区划分正确的是（）。

A.将疫区周边外延3公里内的区域划分为受威胁区

B.将疫区周边外延5公里内的区域划分为受威胁区

C.将疫区周边外延8公里内的区域划分为受威胁区

D.将疫区周边外延10公里内的区域划分为受威胁区

The critical path ______.

A) is the earliest series of events and activities which have the highest technical risk in the project
B) is the series of events and activities which have the highest cost in the project
C) is the longest chain of events and activities from today's date to the end of the project, if the plan represented by the current network plan is executed
D) is an interesting concept, but is has little significance to the project functional managers assigned to the project