Pay attention to limit the information to "the most influential". As far as we know, there were ten business gangs in Ming and Qing Dynasties, namely, Shanxi merchants, Huizhou merchants, Chaoshan merchants, Qin merchants, Shandong merchants, southern Jiangsu merchants, Zhejiang merchants, southern Fujian merchants, Pearl River Delta merchants and Henan merchants. The two most influential business gangs are Shanxi merchants and Huizhou merchants, so item C is correct.
So choose C.