Build a form with multiple choice answers (multiple submit buttons) and validation
I recommend using one of these two modules and adjusting them according to your needs.

https://www.drupal.org/project/quiz

https://www.drupal.org/project/field_quiz

The Field Quiz module provides a simple field that can be used as a simple quiz or multiple choice questions. It provides a field with a textfield and an checkbox combined. If added to a content type the editor of the node can enter multiple answers in the textfields and determine which answers are correct.