Unlike emergency calls that travel through regular telephone lines, where they thus automatically inform the operator of the location and phone number of the caller, cellular calls require emergency operators to determine the location of the caller.
(A) lines, where they thus automatically inform the operator of the location and phone number of the caller, cellular calls require emergency operators to determine the location of the caller
(B) lines and thus automatically inform the operator of the location and phone number of the caller, cellular calls require emergency operators to determine the location of the caller
(C) lines, thus automatically informing the operator of the location and phone number of the caller, the location of the caller on a cellular phone has to be determined by the operator
(D) lines, and thus automatically inform the operator of the location and phone number of the caller, emergency operators have to determine the location of the cellular phone caller
(E) lines, thus automatically informing the operator of the location and phone number of the caller, emergency operators receiving a cellular call have to determine the location of the caller
正确答案是Ｂ想请问一下 这里 travel 与inform平行却省略了that 是由于这个是同位语从句吗？？以前见过一次有人讨论 但不是十分确定～十分谢谢 | 
