I am trying to put together a sheet that contains some drop down lists.

The persone entering data in the sheet will select an item from the first
drop down list, which will then determine the content of the second drop
down list. All the drop down lists will be in the same row, seperate
columns.

E.g.

Drop down list 1

Option A
Option B
Option C

If Option A is selected the second drop down list should then only list
values associated with Option A, e.g.

Option A1
Option A2
Option A3
Option A4

Creating the first drop down list is easy, but how can I get the second drop
down list created based on the selection made in the first drop down list?

Any help appreciated
Kind regards
Pieter