Traveling from Shanghai to Xi'an, pass through the railway hubs in sequence ( ) A. Nanjing, Jinan, Zhengzhou B． Luoyang, Zhengzhou, Xuzhou C. Jinan, Zhengzhou

It can be seen from the picture that when taking a train from Shanghai to Xi'an, the route you should take is from the Beijing-Shanghai Line to Xuzhou. The main railway hubs passing along the way are Nanjing and Xuzhou; and then from the Longhai Line to Lanzhou , the main railway hubs passing along the way are Zhengzhou and Luoyang. Therefore, traveling from Shanghai to Xi'an passes through the railway hubs of Nanjing, Xuzhou, Zhengzhou, and Luoyang in sequence. Therefore option D is consistent with the meaning of the question.

So choose: D.