The steel industry has changed radically over the last two decades, as large, integrated companies such as Bethlehem Steel once conducted operations from mining at one end of the process to shipping at the other have greatly downsized, or in some cases shut down altogether.

A.      as large, integrated companies such as Bethlehem Steel

B.       as large, integrated companies, such as Bethlehem Steel, that

C.      with large, integrated companies, such as Bethlehem Steel, that

D.      while large, integrated companies, such as Bethlehem Steel, that

E.       and large, integrated companies such as Bethlehem Steel

这里答案是B，但跟D有什么区别？

changes......that ...from...to...

而当中那个只是插入了个例子

while放句中表对比转折或者当...时。

这里应该是as引出原因状语从句。