I want to know the answer to the following question:
What at the main Hokkioen urban centers?
All the background I'm provided with is that "In Chinese linguistics, these dialects are known by their classification under the Quanzhang Division (Chinese: 泉漳片; pinyin: Quánzhāng piàn) of Min Nan, which comes from the first characters of the two main Hokkien urban centers Quanzhou and Zhangzhou.". Is that enough to answer the question?
Answer: yes