First make your variable as a normal select box and insert all the options that you need. Note, that this creates new records on the question_choice table.
Open the list of choices (under the related list) in a new window. This will show you the query that is required to get the specific selection of options you just created. Copy the filter (which gives you the encoded query).
Change the type of the variable to list collector. Select the 'question_choice' table and use the copied filter as the reference qualifier.
Result:
