multiple sort combo box

I am new to VBA and having trouble setting up a combo box that sorts based on 4 different column choices. There are 48 columns and a variable number of rows of data beginning on row 17, for which a dynamic range has been created. I need to sort the data in the dynamic range by either column A (Client), Column B (Account Executive), Column C (Dept), or Column D ($ Sales). Columns A, B, and C are alpha characters.

How do I set this up without creating an extra "Sort Order" column on the original data sheet?