Multiple-choice questions in a survey now have a small, but hopefully useful, new feature: comments.
This feature allows you to add an additional field under a multi-choice question which asks the user for further information about why they selected their choice. This should give you an extra dimension when collecting data.
Enable the option in the survey question editor:
Your viewers will be presented with the extra field:
The comment is collected and displayed in your survey reports, as well as being available in CSV and XML exports.