Sentence Correction (SC) | Re: In medieval times, Libya was the principal corridor

chetan2u mikemcgarry sayantanc2k

This question remains a dichotomy. I dont see why A is considered in any way to be understood as corridor passes the merchant goods. Its clearly mentioned that transmission happens by merchants. However is the use of IDIOM "for", which means that corridor is transmitting goods is now superseding the second part of the underlined sentence.
I would really urge a solid verbal perspective from the experts!
Thanks
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