I wonder if any of you can help.
Column A is a dropdown list of departments PCS PKS DIS
Column B is a dropdown list of sub departments of column A PCS = AL, BL or CL; PKS = BA, BT, BX; DIS = LA, LT, LX
Column C is a dropdown of categories based on the Column A list PCS, PKS, ACL ..... 10 - 20 entries in each list.

The problem I am having is that I have set the departments to the categories using data validation but when I want to select the sub departments it obviously wants to give me the list of the categories.
How can I get the dropdown list for column B (sub departments) to show based on the data in column A without impacting column C