Create a table with 1 column, that is dynamically updated from other multiple columns.

I have this senario

I have Column A, B, & C
Each Column is a Single Column Data Table
The First Line in Each Column A, B, & C have a Data Record that Identifies the column. I want that record and all of the records as well from each of A, B, C to update Column F Which is a single column data table as well. So that I can create a drop down data validation list from it. Any Suggestions of how I would go about this.
But I need Column A records to come first. Column B Records to come 2nd, and Column C Records to come last.
See Attachment for Example