Who was the customer in the South Region superstore who bought the most “Hon Multipurpose Stacking Arm Chairs"?
customer refers to "Customer Name"; “Hon Multipurpose Stacking Arm Chairs" is the "Product Name";
SELECT T2.`Customer Name` FROM south_superstore AS T1 INNER JOIN people AS T2 ON T1.`Customer ID` = T2.`Customer ID` INNER JOIN product AS T3 ON T3.`Product ID` = T1.`Product ID` WHERE T3.`Product Name` = 'Hon Multipurpose Stacking Arm Chairs' GROUP BY T2.`Customer Name` ORDER BY COUNT(T2.`Customer Name`) DESC LIMIT 1