GMAT Sentence Correction (SC) | The Anasazi settlements at Chaco Canyon were built on a

Below is my explanation of thisquestion.
"A " is not correct because the verb " were "does not has a subject.
Neither"C " nor"E " is correct because both of them use the past perfect tense " Had been". The past perfect tense links an action which was started and finished before another past action occurred. I do not think we need so.
"D quot; has the very awkward expression " and with each" which comes before the word "connected".
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