Users can add their own answers in different ways in each of Opinion Stage's tools, here are the details:
Polls - polls support a feature that lets users add their own answer rather than selecting an answer from a preset list. The poll creator can view these answers in the statistics report and decide if they would like to add them to the poll (the answers are not auto-added to avoid duplicates/typos/etc). In addition, you can also integrate a lead-form in the poll which can include any number of open-ended fields.
Surveys - support 2 types of open-ended questions - "short answer" & "long answer". You can use these questions anywhere in your survey. In addition, you can also integrate a lead form just before the last screen of the survey that can include any number of open-ended fields.
Trivia & Personality Quizzes - you can integrate a lead form just before the last screen of the quiz that can include any number of open-ended questions.
Classic Forms - classic forms include 2 types of open-ended fields: "text field -single line" & "text field - multiple lines".