I'd like to set up dropdown lists in which their content (list) is determined
from a selection of another dropdown.

Example:

If you select 'project1' from columnA's dropdown list, columnB's dropdown
list content will feature task1, task2, & task3.

While if you select 'project2' from columnA's dropdown list, columnB's
dropdown list content will feature task4, task5, & task6.


I've tried using VLOOKUP to accomplish this task with no success; any advice
will be greatly appreciated.