Google Spreadsheet change dropdown options based on cell value

I have 2 dropdown lists:

I would like the dropdown options inside B2,3 to be driven by the value of A2,3.

So, in the above example, I would ideally like

B2: to contain values from E2:E40
B3: to contain values from F2:F40

I have looked at condition-formatting, but this is the only style. Both A2 and B2 are driving with similar-looking Data-Validation rules as here:

Testable example: https://docs.google.com/spreadsheets/d/1RmGfrO4d9pzeDKONjimwJ0pbr5tYXH-d/edit#gid=229417886