Any question can be made mandatory. Mandatory Questions will require Users to provide an answer at a time of completing a Form.
There are two ways administrators can set Mandatory Questions:
By activating Mandatory Question control in the Question Settings Area
By clicking on an individual Question star in the Active List Area
If you are not an administrator, you will need to have permission to create new Mobile Forms & Surveys. This will depend on a User Role assigned to you by your administrator.