设栈S和队列Q的初始状态为空，元素a、b、c、d、e和f依次通过栈S，一个元素出栈后即进入队列Q，若6个元素出队的顺序是b、d、c、f、e、a，则栈S的容量至少应该是( )。

A．6

B．4

C．3

D．2

The Simple Network Management Protocol (SNMP)is an (66) protocol that facilitates the exchange of management information between (67) . It is part of the Transmission Control Protocol/Internet Protocol(TCP/IP) protocol suite. SNMP enables network (68) to manage network performance, find and sole network problems, and plan for (69) An SNMP -managed network consists of three key components: managed devices , (70) ,and network -management systems .

A. network growth B. network structure C. network architectureD. network servers