First of all I'd like to point out that sending sql statements directly from the client (your 'questions' chooser, as any other display being a client-side entity), is considered a major security risk, as it provides an opening for performing SQL Injection (see this post for additional details on this issue).
Instead, your chooser should include only the 'questions' you wish to display, and the selected questions should be passed to a Service-based process, which will issue the required statement. Here's a simplified example:
However, if we take it outside the sql-statement-specific context, and ask: "How do we display certain values in the chooser, where each value represents one or more additional values?".
This is certainly a valid question.
For the answer, I quote from the documentation for chooser (available via [F1], Help -> Help Contents or here):
"Notice that <Value> and <Options> should be of the same type (e.g. both Text, both Date, or whatever data type you want). If they have a composite data type, the drop-down list displays the first text field it contains. For example, if it contains a numeric field named Id and a text field named Name, then the Name values of each of the data structures in <Options> is displayed."
Note that a composite data type is a data structure.
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