We have 2 forms, one form with quiz questions and answers and another form that uses the data from form 1 and allows users to write their own answers, to answer the quiz
Answer field is set to be restricted (view) only to users from confluence-administrators security group
Quiz for user:
This is the UI visible by quiz admin (with answers) Correct answer is taken from "quiz" form using smart field reference (quiz.answer)
So, basically the idea is that you create 2 forms - one with a quiz and another one with answers that you r users will record
And connect the forms via the Smart fields
Storage format for complete solution: