Re-tarball your course (how to do this in Terminal here)
Import the tarball
Notes
Although the polls will render correctly in Studio, you will not be able to edit them in Studio. You will need to follow the export/import process outlined above to make any edits to your polls.
You will be editing the raw XML code of your course to add this feature. We do not recommend attempting to edit other areas of your course in this method unless you have the necessary background and training.
A CSV for student responses to the problem is not currently available for polls, though the aggregate data is easily obtained directly in the problem.