答案是什么？

我是来求教的。我当时选了C，爸爸选A。她的老师和隔壁班老师商量后选A。
然后我查到这个link
http://www.answers.com/Q/How_do_you_punctuate_three_cities_and_states_in_a_sentence
“Whenever a sentence requires commas that would make the series commas seem redundant or confusing the correct punctuation is the semi-colon, e.g., Portland, Birmingham, and Washington can be written using the series comma but if the Portland needed to be specified as to the state and the Birmingham is in England and the Washington was not the District of Columbia, then it would look like this: Portland, Oregon; Birmingham, England; and Washington North Carolina. ”
按这个理论是选C。不过她爸一直就很怀疑网上的东西的可靠性。
又查到第二个link
https://answers.yahoo.com/question/index?qid=20071018084251AA7wgAT
“Dallas, Texas; Chicago, Illinois; Appleton, Wisconsin; etc” 也是支持C
还有没有更有力的意见啊？反正是学习。