请教补充250的第177题

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

C的that紧跟在foreheads后面难道不会被认为是修饰foreheads的？虽然我认为其他选项也明显有问题。要是非选的话我宁可选B

C的that的确是紧跟foreheads，但是，应该注意that前是有逗号的，从ETS限定性和非限定性定语从句的明确分工来看，如果that是用来修饰foreheads的话，要么就换用which，要么这里的逗号就是一个错误；当然，还有一种理解，那就是that前的逗号部分是一个插入语，而that是修饰插入语前的就近名词sounds，于是，理解上就没有问题了。其实，这种限定性定语从句分割修饰的例子在阅读中更为多见，在语法中也时有出现，仔细观察一下会逐渐习惯的。

至于B，首先，that are可以被省略而不改变意思和逻辑；其次，this逻辑上指代sounds(一个复数名词)，是个语法错误。

一家之言，望指教。