I'm doing a personal project where I have a quiz with a number of boolean questions. Each question will have a two answer choices "true" and "false". Based on the selected answer, a new question will be asked with the similar pattern and based on that an another question. Any question may have any or no number of sub-questions.
The last questions in the tree (E, D) and questions with no sub-questions (F) will also store the correct answer from either "true" or "false".
The alphabets A,B,C,D,E,F are questions. A quiz can have any number of master questions (like A), sub-questions like (like B,C,D,E) and individual questions (like F).
Kindly help me design a simple database schema for for this kind of quiz. I'm open to both relational (mysql) and document (mongodb) databases.