WLANs are increasingly popular because the

问题：

WLANs are increasingly popular because they enable cost-effective connections amongpeople, applications and data that were not possible, or not cost-effective, in the past.For example, WLAN-based applications can enable fine-grained management of supply and distribution （1） to improve their efficiency and reduce （2）. WLANs can also enable entirely new business processes. To cite but one example, hospitals are using WLAN-enabled point-of-care applications to reduce errors and improve overall （3） care.WLAN management solutions provide a variety of other benefits that can be substantial but difficult to measure. For example, they can protect corporate data by preventing （4）through rogue access points. They help control salary costs, by allowing IT staffs to manage larger networks without adding staff. And they can improve overall network management by integrating with customers’ existing systems, such as OpenView. Fortunately, it isn’t necessary to measure these benefits to justify investing in WLAN management solutions, which can quickly pay for themselves simply by minimizing time-consuming（5）and administrative chores.

4（）

A.intrusion 

B.aggression 

C.inbreak 

D.infall