Trying to create dynamic validation List (s)

After referring to one cell I need the data list to populate. If the
reference cell changes the data list changes.

Example: -

Reference cell = A1
Columns D2, E2 and F2 have data populated
Columns have headings, One, Two and Three

If in cell A1 I input One, the List (DV) is from D2 to "list" end.
If in cell A1 if I input Two, the List (DV) is from E2 to "list" end
If in cell A1 if I input Three, the List (DV) is from F2 to "list" end

Help greatly appreciated!
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Crunchies