QS:Mandatory
From LimeSurvey Manual
Mandatory
Description
This option allows the survey administrators to request their respondents to answer certain survey questions. If the mandatory questions are not answered, the respondents will not be able to proceed further. If you have a question with multiple subquestions, and you require only certain subquestions to be answered, use the minimum answer attribute located under the Logic tab.

Available options
- On - Question must be answered before the participant can proceed to the next page - the answer option 'No answer' is never shown.
- Soft - If the question is not answered, a warning is shown when trying to proceed to the next page - however, the participant can choose to ignore the warning and proceed. Note that the 'No answer' option is still shown (if activated in survey presentation settings)
- Off (default) - Question can be left unanswered