What about something along the lines of this structure:
{
"Questions" :
[
{
"QuestionNumber": "Q1",
"QuestionType" : "YESNO",
"QuestionText" : "Are you happy today?",
"Answers" :
[
{
"Text" : "YES",
"NextQuestionIfAnswered" : "Q9"
},
{
"Text" : "No",
"NextQuestionIfAnswered" : "Q2"
}
],
},
{
"QuestionNumber": "Q2",
"QuestionType" : "MULTIPLE",
"QuestionText" : "Why aren't you happy?",
"Answers" :
[
{
"Text" : "Dog died",
"NextQuestionIfAnswered" : ""
},
{
"Text" : "I'm just generally sad",
"NextQuestionIfAnswered" : ""
}
],
},
{
"QuestionNumber": "Q9",
"QuestionType" : "TEXTBOX",
"QuestionText" : "Type why you are happy into the box below",
"Answers" : []
}
]
}
So you have an array of questions, each with a question number, question type (used for rendering decisions), and each of the possible answers includes the question number that you navigate to when the specified answer is selected.
You could store the user's answers to each question in this document as well by adding an userAnswer property on each of the "Answers" in the array. But depending on your number of users, you may want to keep this in a separate collection.