There was such a long line at the exhibition ______ we had to wa

There was such a long line at the exhibition ______ we had to wait for about half an hour.
A、as
B、that
C、so
D、hence
【正确答案】：B
【题目解析】：句型"such...that"表示“如此……以至于”，that引导出结果状语从句。