On his way to the top of the mountain, the boy dropped his stick, ______he______ it. [ ]

A. and; stopped getting                    

B. so; stopped getting  

C. /; stopped to get                      

D. so; stopped to get

为解决计算机与打印机之间速度不匹配的问题，通常设置一个打印数据缓冲区，主机将要输出的数据依次写入该缓冲区，而打印机则依次从该缓冲区中取出数据。该缓冲区的逻辑结构应该是（）。

A.栈

B.队列

C.树

D.图