Read this: Into the first half of the twentieth century after the establishment of ROC, Nanjing gradually shifted from being a production hub towards being a heavy consumption city, mainly because of the rapid expansion of its wealthy population after Nanjing once again regained the political spotlight of China. A number of huge department stores such as Zhongyang Shangchang sprouted up, attracting merchants from all over China to sell their products in Nanjing. In 1933, the revenue generated by the food and entertainment industry in the city exceeded the sum of the output of the manufacturing and agriculture industry. One third of the city population worked in the service industry, .
Now answer this question, if there is an answer (If it cannot be answered, return "unanswerable"): What mostly caused the shift to a consumer city?
the rapid expansion of its wealthy population