In multiple choices names, blanks are invalid. It is also recommended not to use blanks for select_one choices. See
- https://community.kobotoolbox.org/t/form-preview-error-while-cascading-the-options-to-the-previous-question/34228/4
- https://xlsform.org/en/#choice-names.
You can find a lot of examples with the search function of the forum, e.g. How to create a multi layer cascading select question? - #19 by Kal_Lam.
Hint: When you reference select_one, you can just reference directly as ${select_oneVariable}. selected(…) is only needed for select_multiple.
