The subway exit of the South Campus of Zhongshan Second Hospital is Exit A. Take the subway from Guangzhou South Station to the South Campus of Zhongshan Second Hospital. After getting off the bus, you need to go to Exit A, walk along Dong Xiao South Road, and then turn to Yifeng Road, and you can reach the South Campus of Zhongshan Second Hospital. Therefore, Exit A is the correct exit to reach the subway station in the South Campus of the Second Hospital of Zhongshan.