Most electronic devices of this kind,___ manufactrued for such purposeds,are tightly packed.

题目

Most electronic devices of this kind,___ manufactrued for such purposeds,are tightly packed.
A.it is
B.which
C.as are
D.that are
-------------再翻译下

答案

B.which
大多数这种型号的为了专用目的制造的电子器具,都有很紧的包装的.