Set the choices as one field instead of multiple fields in your data type Question. This field should be a list of texts (when you create a new field in Data > Data Types > Question, just check the box « this field is a list »). You can then add the different choices to this list in App Data.
You option caption would then be Current Option’s Choices
@nyalova you should get choices for a Question, not a Question’s Title.
In general, you must set the data source to a Thing, then display this Thing’s fields in elements on the page. I would suggest you to go through the lessons to understand the basic logic