请教 大全117

    177.
            Believed to originate from a small area on their foreheads, elephants emit low-frequency    sounds that may be used as a secret language to communicate with other members of the herd.

(A) Believed to originate from a small area on their foreheads, elephants emit low-frequency sounds that may be used

(B) Elephants emit low-frequency sounds that are believed to originate from a small area on their foreheads, and they may use this

(C) Elephants emit low-frequency sounds, believed to originate from a small area on their foreheads, that they may use

(D) Originating, it is believed, from a small area on their foreheads; elephants emit low-frequency sounds they may use（C）

(E) Originating, it is believed, from a small area on their foreheads, low-frequency sounds are emitted by elephants that may be used

请问E选项中 that 为什么不可以看做是跳跃指代主语low-frequency sounds 呢？

呵呵，越看越昏了哈，小声请教，请NN指点一下。

   能说一下that定于从句后置不可以吗？搞不清楚啊！！！